diff --git a/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/OidcTenantConfig.java b/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/OidcTenantConfig.java
index 4c8cdfc3beb36..f261186045c1c 100644
--- a/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/OidcTenantConfig.java
+++ b/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/OidcTenantConfig.java
@@ -926,6 +926,13 @@ public enum ResponseMode {
         @ConfigItem
         public Optional<List<String>> scopes = Optional.empty();
 
+        /**
+         * The separator which is used when more than one scope is configured.
+         * A single space is used by default.
+         */
+        @ConfigItem
+        public Optional<String> scopeSeparator = Optional.empty();
+
         /**
          * Require that ID token includes a `nonce` claim which must match `nonce` authentication request query parameter.
          * Enabling this property can help mitigate replay attacks.
@@ -1342,6 +1349,14 @@ public Optional<String> getStateSecret() {
         public void setStateSecret(Optional<String> stateSecret) {
             this.stateSecret = stateSecret;
         }
+
+        public Optional<String> getScopeSeparator() {
+            return scopeSeparator;
+        }
+
+        public void setScopeSeparator(String scopeSeparator) {
+            this.scopeSeparator = Optional.of(scopeSeparator);
+        }
     }
 
     /**
diff --git a/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/OidcUtils.java b/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/OidcUtils.java
index a436e2456ca7f..38b4c6543fe62 100644
--- a/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/OidcUtils.java
+++ b/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/OidcUtils.java
@@ -82,6 +82,7 @@ public final class OidcUtils {
     public static final String STATE_COOKIE_NAME = "q_auth";
     public static final Integer MAX_COOKIE_VALUE_LENGTH = 4096;
     public static final String POST_LOGOUT_COOKIE_NAME = "q_post_logout";
+    public static final String DEFAULT_SCOPE_SEPARATOR = " ";
     static final String UNDERSCORE = "_";
     static final String CODE_ACCESS_TOKEN_RESULT = "code_flow_access_token_result";
     static final String COMMA = ",";
@@ -552,6 +553,9 @@ static OidcTenantConfig mergeTenantConfig(OidcTenantConfig tenant, OidcTenantCon
         if (tenant.authentication.scopes.isEmpty()) {
             tenant.authentication.scopes = provider.authentication.scopes;
         }
+        if (tenant.authentication.scopeSeparator.isEmpty()) {
+            tenant.authentication.scopeSeparator = provider.authentication.scopeSeparator;
+        }
         if (tenant.authentication.addOpenidScope.isEmpty()) {
             tenant.authentication.addOpenidScope = provider.authentication.addOpenidScope;
         }
@@ -661,7 +665,8 @@ public void handle(Void event) {
     }
 
     public static String encodeScopes(OidcTenantConfig oidcConfig) {
-        return OidcCommonUtils.urlEncode(String.join(" ", getAllScopes(oidcConfig)));
+        return OidcCommonUtils.urlEncode(String.join(oidcConfig.authentication.scopeSeparator.orElse(DEFAULT_SCOPE_SEPARATOR),
+                getAllScopes(oidcConfig)));
     }
 
     public static List<String> getAllScopes(OidcTenantConfig oidcConfig) {
diff --git a/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/providers/KnownOidcProviders.java b/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/providers/KnownOidcProviders.java
index d59f5fec66fb4..36bc6425e2e49 100644
--- a/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/providers/KnownOidcProviders.java
+++ b/extensions/oidc/runtime/src/main/java/io/quarkus/oidc/runtime/providers/KnownOidcProviders.java
@@ -172,6 +172,7 @@ private static OidcTenantConfig strava() {
 
         ret.getToken().setVerifyAccessTokenWithUserInfo(true);
         ret.getCredentials().getClientSecret().setMethod(Method.QUERY);
+        ret.getAuthentication().setScopeSeparator(",");
 
         return ret;
     }
diff --git a/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/KnownOidcProvidersTest.java b/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/KnownOidcProvidersTest.java
index 1bafcd14e7b91..715fe4a563fe6 100644
--- a/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/KnownOidcProvidersTest.java
+++ b/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/KnownOidcProvidersTest.java
@@ -455,6 +455,7 @@ public void testAcceptStravaProperties() {
         assertFalse(config.getAuthentication().idTokenRequired.get());
         assertEquals(Method.QUERY, config.credentials.clientSecret.method.get());
         assertEquals("/strava", config.authentication.redirectPath.get());
+        assertEquals(",", config.authentication.scopeSeparator.get());
     }
 
     @Test
@@ -472,6 +473,7 @@ public void testOverrideStravaProperties() {
         tenant.token.setVerifyAccessTokenWithUserInfo(false);
         tenant.credentials.clientSecret.setMethod(Method.BASIC);
         tenant.authentication.setRedirectPath("/fitness-app");
+        tenant.authentication.setScopeSeparator(" ");
 
         OidcTenantConfig config = OidcUtils.mergeTenantConfig(tenant, KnownOidcProviders.provider(Provider.STRAVA));
 
@@ -485,6 +487,7 @@ public void testOverrideStravaProperties() {
         assertFalse(config.token.verifyAccessTokenWithUserInfo.get());
         assertEquals(Method.BASIC, config.credentials.clientSecret.method.get());
         assertEquals("/fitness-app", config.authentication.redirectPath.get());
+        assertEquals(" ", config.authentication.scopeSeparator.get());
     }
 
     @Test
diff --git a/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/OidcUtilsTest.java b/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/OidcUtilsTest.java
index 40b139e0b9522..68ee4e1c65a2c 100644
--- a/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/OidcUtilsTest.java
+++ b/extensions/oidc/runtime/src/test/java/io/quarkus/oidc/runtime/OidcUtilsTest.java
@@ -301,6 +301,15 @@ public void testEncodeAllScopes() throws Exception {
         assertEquals("openid+a%3A1+b%3A2+c+d", OidcUtils.encodeScopes(config));
     }
 
+    @Test
+    public void testEncodeAllScopesWithCustomSeparator() throws Exception {
+        OidcTenantConfig config = new OidcTenantConfig();
+        config.authentication.setScopeSeparator(",");
+        config.authentication.setScopes(List.of("a:1", "b:2"));
+        config.authentication.setExtraParams(Map.of("scope", "c,d"));
+        assertEquals("openid%2Ca%3A1%2Cb%3A2%2Cc%2Cd", OidcUtils.encodeScopes(config));
+    }
+
     public static JsonObject read(InputStream input) throws IOException {
         try (BufferedReader buffer = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8))) {
             return new JsonObject(buffer.lines().collect(Collectors.joining("\n")));