diff --git a/output/json/json.go b/output/json/json.go
index f2d8ea36806..49591d2f951 100644
--- a/output/json/json.go
+++ b/output/json/json.go
@@ -32,7 +32,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-// TODO: add option for emitting proper JSON files (https://github.com/loadimpact/k6/issues/1052)
+// TODO: add option for emitting proper JSON files (https://github.com/loadimpact/k6/issues/737)
 const flushPeriod = 200 * time.Millisecond // TODO: make this configurable
 
 // Output funnels all passed metrics to an (optionally gzipped) JSON file.
@@ -47,6 +47,7 @@ type Output struct {
 	encoder     *stdlibjson.Encoder
 	closeFn     func() error
 	seenMetrics map[string]struct{}
+	thresholds  map[string][]*stats.Threshold
 }
 
 // New returns a new JSON output.
@@ -118,6 +119,15 @@ func (o *Output) Stop() error {
 	return o.closeFn()
 }
 
+// SetThresholds receives the thresholds before the output is Start()-ed.
+func (o *Output) SetThresholds(thresholds map[string]stats.Thresholds) {
+	ths := make(map[string][]*stats.Threshold)
+	for name, t := range thresholds {
+		ths[name] = append(ths[name], t.Thresholds...)
+	}
+	o.thresholds = ths
+}
+
 func (o *Output) flushMetrics() {
 	samples := o.GetBufferedSamples()
 	start := time.Now()
@@ -127,6 +137,7 @@ func (o *Output) flushMetrics() {
 		count += len(samples)
 		for _, sample := range samples {
 			sample := sample
+			sample.Metric.Thresholds.Thresholds = o.thresholds[sample.Metric.Name]
 			o.handleMetric(sample.Metric)
 			err := o.encoder.Encode(WrapSample(sample))
 			if err != nil {
diff --git a/output/json/json_test.go b/output/json/json_test.go
index da104f95261..e273a3871aa 100644
--- a/output/json/json_test.go
+++ b/output/json/json_test.go
@@ -71,9 +71,8 @@ func generateTestMetricSamples(t *testing.T) ([]stats.SampleContainer, func(io.R
 		}, Time: time2, Tags: connTags},
 		stats.Sample{Time: time3, Metric: metric2, Value: float64(5), Tags: stats.NewSampleTags(map[string]string{"tag3": "val3"})},
 	}
-	// TODO: fix JSON thresholds (https://github.com/loadimpact/k6/issues/1052)
 	expected := []string{
-		`{"type":"Metric","data":{"name":"my_metric1","type":"gauge","contains":"default","tainted":null,"thresholds":[],"submetrics":null,"sub":{"name":"","parent":"","suffix":"","tags":null}},"metric":"my_metric1"}`,
+		`{"type":"Metric","data":{"name":"my_metric1","type":"gauge","contains":"default","tainted":null,"thresholds":["rate<0.01", "p(99)<250"],"submetrics":null,"sub":{"name":"","parent":"","suffix":"","tags":null}},"metric":"my_metric1"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:10Z","value":1,"tags":{"tag1":"val1"}},"metric":"my_metric1"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:10Z","value":2,"tags":{"tag2":"val2"}},"metric":"my_metric1"}`,
 		`{"type":"Metric","data":{"name":"my_metric2","type":"counter","contains":"data","tainted":null,"thresholds":[],"submetrics":null,"sub":{"name":"","parent":"","suffix":"","tags":null}},"metric":"my_metric2"}`,
@@ -94,6 +93,8 @@ func TestJsonOutputStdout(t *testing.T) {
 		StdOut: stdout,
 	})
 	require.NoError(t, err)
+
+	setThresholds(t, out)
 	require.NoError(t, out.Start())
 
 	samples, validateResults := generateTestMetricSamples(t)
@@ -130,6 +131,8 @@ func TestJsonOutputFile(t *testing.T) {
 		ConfigArgument: "/json-output",
 	})
 	require.NoError(t, err)
+
+	setThresholds(t, out)
 	require.NoError(t, out.Start())
 
 	samples, validateResults := generateTestMetricSamples(t)
@@ -156,6 +159,8 @@ func TestJsonOutputFileGzipped(t *testing.T) {
 		ConfigArgument: "/json-output.gz",
 	})
 	require.NoError(t, err)
+
+	setThresholds(t, out)
 	require.NoError(t, out.Start())
 
 	samples, validateResults := generateTestMetricSamples(t)
@@ -185,3 +190,15 @@ func TestWrapMetricWithMetricPointer(t *testing.T) {
 	out := wrapMetric(&stats.Metric{})
 	assert.NotEqual(t, out, (*Envelope)(nil))
 }
+
+func setThresholds(t *testing.T, out output.Output) {
+	t.Helper()
+
+	jout, ok := out.(*Output)
+	require.True(t, ok)
+
+	ts, err := stats.NewThresholds([]string{"rate<0.01", "p(99)<250"})
+	require.NoError(t, err)
+
+	jout.SetThresholds(map[string]stats.Thresholds{"my_metric1": ts})
+}