diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira.tsx
index 0179cfbffdfea..81f0bbfe8a02f 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira.tsx
@@ -27,8 +27,12 @@ const validateConnector = (action: JiraActionConnector): ValidationResult => {
     errors.apiUrl = [...errors.apiUrl, i18n.API_URL_REQUIRED];
   }
 
-  if (action.config.apiUrl && !isValidUrl(action.config.apiUrl, 'https:')) {
-    errors.apiUrl = [...errors.apiUrl, i18n.API_URL_INVALID];
+  if (action.config.apiUrl) {
+    if (!isValidUrl(action.config.apiUrl)) {
+      errors.apiUrl = [...errors.apiUrl, i18n.API_URL_INVALID];
+    } else if (!isValidUrl(action.config.apiUrl, 'https:')) {
+      errors.apiUrl = [...errors.apiUrl, i18n.API_URL_REQUIRE_HTTPS];
+    }
   }
 
   if (!action.config.projectKey) {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira_connectors.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira_connectors.tsx
index 35c6bd7af00ab..64ae752afa901 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira_connectors.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/jira_connectors.tsx
@@ -98,7 +98,6 @@ const JiraConnectorFields: React.FC<ActionConnectorFieldsProps<JiraActionConnect
               readOnly={readOnly}
               value={apiUrl || ''} // Needed to prevent uncontrolled input error when value is undefined
               data-test-subj="apiUrlFromInput"
-              placeholder="https://<site-url>"
               onChange={(evt) => handleOnChangeActionConfig('apiUrl', evt.target.value)}
               onBlur={() => {
                 if (!apiUrl) {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/translations.ts b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/translations.ts
index f6db56e188322..6f45316ff4433 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/translations.ts
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/jira/translations.ts
@@ -41,6 +41,13 @@ export const API_URL_INVALID = i18n.translate(
   }
 );
 
+export const API_URL_REQUIRE_HTTPS = i18n.translate(
+  'xpack.triggersActionsUI.components.builtinActionTypes.jira.requireHttpsApiUrlTextField',
+  {
+    defaultMessage: 'URL must start with https://.',
+  }
+);
+
 export const JIRA_PROJECT_KEY_LABEL = i18n.translate(
   'xpack.triggersActionsUI.components.builtinActionTypes.jira.projectKey',
   {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient.tsx
index 1b27968c04fd3..6d57fc98fe20f 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient.tsx
@@ -31,8 +31,12 @@ const validateConnector = (action: ResilientActionConnector): ValidationResult =
     errors.apiUrl = [...errors.apiUrl, i18n.API_URL_REQUIRED];
   }
 
-  if (action.config.apiUrl && !isValidUrl(action.config.apiUrl, 'https:')) {
-    errors.apiUrl = [...errors.apiUrl, i18n.API_URL_INVALID];
+  if (action.config.apiUrl) {
+    if (!isValidUrl(action.config.apiUrl)) {
+      errors.apiUrl = [...errors.apiUrl, i18n.API_URL_INVALID];
+    } else if (!isValidUrl(action.config.apiUrl, 'https:')) {
+      errors.apiUrl = [...errors.apiUrl, i18n.API_URL_REQUIRE_HTTPS];
+    }
   }
 
   if (!action.config.orgId) {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient_connectors.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient_connectors.tsx
index fe2aa341a7111..68626e8a0d3fa 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient_connectors.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/resilient_connectors.tsx
@@ -98,7 +98,6 @@ const ResilientConnectorFields: React.FC<ActionConnectorFieldsProps<ResilientAct
               readOnly={readOnly}
               value={apiUrl || ''} // Needed to prevent uncontrolled input error when value is undefined
               data-test-subj="apiUrlFromInput"
-              placeholder="https://<site-url>"
               onChange={(evt) => handleOnChangeActionConfig('apiUrl', evt.target.value)}
               onBlur={() => {
                 if (!apiUrl) {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/translations.ts b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/translations.ts
index b45f898d7d809..65d08c9f7de68 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/translations.ts
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/resilient/translations.ts
@@ -41,6 +41,13 @@ export const API_URL_INVALID = i18n.translate(
   }
 );
 
+export const API_URL_REQUIRE_HTTPS = i18n.translate(
+  'xpack.triggersActionsUI.components.builtinActionTypes.resilient.requireHttpsApiUrlTextField',
+  {
+    defaultMessage: 'URL must start with https://.',
+  }
+);
+
 export const ORG_ID_LABEL = i18n.translate(
   'xpack.triggersActionsUI.components.builtinActionTypes.resilient.orgId',
   {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow.tsx
index 8396497a6e284..9cc689d8f48b1 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow.tsx
@@ -30,8 +30,12 @@ const validateConnector = (action: ServiceNowActionConnector): ValidationResult
     errors.apiUrl = [...errors.apiUrl, i18n.API_URL_REQUIRED];
   }
 
-  if (action.config.apiUrl && !isValidUrl(action.config.apiUrl, 'https:')) {
-    errors.apiUrl = [...errors.apiUrl, i18n.API_URL_INVALID];
+  if (action.config.apiUrl) {
+    if (!isValidUrl(action.config.apiUrl)) {
+      errors.apiUrl = [...errors.apiUrl, i18n.API_URL_INVALID];
+    } else if (!isValidUrl(action.config.apiUrl, 'https:')) {
+      errors.apiUrl = [...errors.apiUrl, i18n.API_URL_REQUIRE_HTTPS];
+    }
   }
 
   if (!action.secrets.username) {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow_connectors.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow_connectors.tsx
index d351b32c3bb06..66de29c68de2b 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow_connectors.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/servicenow_connectors.tsx
@@ -104,7 +104,6 @@ const ServiceNowConnectorFields: React.FC<ActionConnectorFieldsProps<
               readOnly={readOnly}
               value={apiUrl || ''} // Needed to prevent uncontrolled input error when value is undefined
               data-test-subj="apiUrlFromInput"
-              placeholder="https://<site-url>"
               onChange={(evt) => handleOnChangeActionConfig('apiUrl', evt.target.value)}
               onBlur={() => {
                 if (!apiUrl) {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/translations.ts b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/translations.ts
index 67e94bc136cf9..312cb9844bd75 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/translations.ts
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/servicenow/translations.ts
@@ -41,6 +41,13 @@ export const API_URL_INVALID = i18n.translate(
   }
 );
 
+export const API_URL_REQUIRE_HTTPS = i18n.translate(
+  'xpack.triggersActionsUI.components.builtinActionTypes.servicenow.requireHttpsApiUrlTextField',
+  {
+    defaultMessage: 'URL must start with https://.',
+  }
+);
+
 export const AUTHENTICATION_LABEL = i18n.translate(
   'xpack.triggersActionsUI.components.builtinActionTypes.servicenow.authenticationLabel',
   {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.test.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.test.tsx
index 78f4161cac827..01343dcd472ce 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.test.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.test.tsx
@@ -31,11 +31,11 @@ describe('slack connector validation', () => {
   test('connector validation succeeds when connector config is valid', () => {
     const actionConnector = {
       secrets: {
-        webhookUrl: 'http:\\test',
+        webhookUrl: 'https:\\test',
       },
       id: 'test',
-      actionTypeId: '.email',
-      name: 'email',
+      actionTypeId: '.slack',
+      name: 'slack',
       config: {},
     } as SlackActionConnector;
 
@@ -46,12 +46,12 @@ describe('slack connector validation', () => {
     });
   });
 
-  test('connector validation fails when connector config is not valid', () => {
+  test('connector validation fails when connector config is not valid - no webhook url', () => {
     const actionConnector = {
       secrets: {},
       id: 'test',
-      actionTypeId: '.email',
-      name: 'email',
+      actionTypeId: '.slack',
+      name: 'slack',
       config: {},
     } as SlackActionConnector;
 
@@ -61,6 +61,42 @@ describe('slack connector validation', () => {
       },
     });
   });
+
+  test('connector validation fails when connector config is not valid - invalid webhook protocol', () => {
+    const actionConnector = {
+      secrets: {
+        webhookUrl: 'http:\\test',
+      },
+      id: 'test',
+      actionTypeId: '.slack',
+      name: 'slack',
+      config: {},
+    } as SlackActionConnector;
+
+    expect(actionTypeModel.validateConnector(actionConnector)).toEqual({
+      errors: {
+        webhookUrl: ['Webhook URL must start with https://.'],
+      },
+    });
+  });
+
+  test('connector validation fails when connector config is not valid - invalid webhook url', () => {
+    const actionConnector = {
+      secrets: {
+        webhookUrl: 'h',
+      },
+      id: 'test',
+      actionTypeId: '.slack',
+      name: 'slack',
+      config: {},
+    } as SlackActionConnector;
+
+    expect(actionTypeModel.validateConnector(actionConnector)).toEqual({
+      errors: {
+        webhookUrl: ['Webhook URL is invalid.'],
+      },
+    });
+  });
 });
 
 describe('slack action params validation', () => {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.tsx
index 23c76f327008b..1df78b4c9312d 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack.tsx
@@ -7,6 +7,7 @@ import { lazy } from 'react';
 import { i18n } from '@kbn/i18n';
 import { ActionTypeModel, ValidationResult } from '../../../../types';
 import { SlackActionParams, SlackSecrets, SlackActionConnector } from '../types';
+import { isValidUrl } from '../../../lib/value_validators';
 
 export function getActionType(): ActionTypeModel<unknown, SlackSecrets, SlackActionParams> {
   return {
@@ -39,6 +40,26 @@ export function getActionType(): ActionTypeModel<unknown, SlackSecrets, SlackAct
             }
           )
         );
+      } else if (action.secrets.webhookUrl) {
+        if (!isValidUrl(action.secrets.webhookUrl)) {
+          errors.webhookUrl.push(
+            i18n.translate(
+              'xpack.triggersActionsUI.components.builtinActionTypes.slackAction.error.invalidWebhookUrlText',
+              {
+                defaultMessage: 'Webhook URL is invalid.',
+              }
+            )
+          );
+        } else if (!isValidUrl(action.secrets.webhookUrl, 'https:')) {
+          errors.webhookUrl.push(
+            i18n.translate(
+              'xpack.triggersActionsUI.components.builtinActionTypes.slackAction.error.requireHttpsWebhookUrlText',
+              {
+                defaultMessage: 'Webhook URL must start with https://.',
+              }
+            )
+          );
+        }
       }
       return validationResult;
     },
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack_connectors.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack_connectors.tsx
index 3e744eff07797..0b37f340f01e2 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack_connectors.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/slack/slack_connectors.tsx
@@ -47,7 +47,6 @@ const SlackActionFields: React.FunctionComponent<ActionConnectorFieldsProps<
             isInvalid={errors.webhookUrl.length > 0 && webhookUrl !== undefined}
             name="webhookUrl"
             readOnly={readOnly}
-            placeholder="Example: https://hooks.slack.com/services"
             value={webhookUrl || ''}
             data-test-subj="slackWebhookUrlInput"
             onChange={(e) => {
diff --git a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/webhook/webhook_connectors.tsx b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/webhook/webhook_connectors.tsx
index 15d4c6c30450e..1a9de48ccce3a 100644
--- a/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/webhook/webhook_connectors.tsx
+++ b/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_action_types/webhook/webhook_connectors.tsx
@@ -261,7 +261,6 @@ const WebhookActionConnectorFields: React.FunctionComponent<ActionConnectorField
               fullWidth
               readOnly={readOnly}
               value={url || ''}
-              placeholder="https://<site-url> or http://<site-url>"
               data-test-subj="webhookUrlText"
               onChange={(e) => {
                 editActionConfig('url', e.target.value);