diff --git a/backend/controller/ingress/ingress.go b/backend/controller/ingress/ingress.go
index a4d7c67a58..e317bb477c 100644
--- a/backend/controller/ingress/ingress.go
+++ b/backend/controller/ingress/ingress.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"math/rand"
 	"net/http"
+	"net/url"
 	"reflect"
 	"strconv"
 	"strings"
@@ -124,9 +125,13 @@ func buildRequestMap(route *dal.IngressRoute, r *http.Request) (map[string]any,
 			requestMap[k] = v
 		}
 	default:
-		// TODO: Support query params correctly for map and array
-		for key, value := range r.URL.Query() {
-			requestMap[key] = value[len(value)-1]
+		queryMap, err := parseQueryParams(r.URL.Query())
+		if err != nil {
+			return nil, fmt.Errorf("HTTP query params are not valid: %w", err)
+		}
+
+		for key, value := range queryMap {
+			requestMap[key] = value
 		}
 	}
 
@@ -249,3 +254,59 @@ func validateValue(fieldType schema.Type, path path, value any, sch *schema.Sche
 	}
 	return nil
 }
+
+func parseQueryParams(values url.Values) (map[string]any, error) {
+	if jsonStr, ok := values["@json"]; ok {
+		if len(values) > 1 {
+			return nil, fmt.Errorf("only '@json' parameter is allowed, but other parameters were found")
+		}
+		if len(jsonStr) > 1 {
+			return nil, fmt.Errorf("'@json' parameter must be provided exactly once")
+		}
+
+		return decodeQueryJSON(jsonStr[0])
+	}
+
+	queryMap := make(map[string]any)
+	for key, value := range values {
+		if hasInvalidQueryChars(key) {
+			return nil, fmt.Errorf("complex key '%s' is not supported, use '@json=' instead", key)
+		}
+		if len(value) == 1 {
+			if hasInvalidQueryChars(value[0]) {
+				return nil, fmt.Errorf("complex value '%s' is not supported, use '@json=' instead", value[0])
+			}
+			queryMap[key] = value[0]
+		} else {
+			for _, v := range value {
+				if hasInvalidQueryChars(v) {
+					return nil, fmt.Errorf("complex value '%s' is not supported, use '@json=' instead", v)
+				}
+			}
+			// Assign as an array of strings if there are multiple values for the key
+			queryMap[key] = value
+		}
+	}
+
+	return queryMap, nil
+}
+
+func decodeQueryJSON(query string) (map[string]any, error) {
+	decodedJSONStr, err := url.QueryUnescape(query)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode '@json' query parameter: %w", err)
+	}
+
+	// Unmarshal the JSON string into a map
+	var resultMap map[string]any
+	err = json.Unmarshal([]byte(decodedJSONStr), &resultMap)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse '@json' query parameter: %w", err)
+	}
+
+	return resultMap, nil
+}
+
+func hasInvalidQueryChars(s string) bool {
+	return strings.ContainsAny(s, "{}[]|\\^`")
+}
diff --git a/backend/controller/ingress/ingress_test.go b/backend/controller/ingress/ingress_test.go
index 1e0a361abc..8588830e7d 100644
--- a/backend/controller/ingress/ingress_test.go
+++ b/backend/controller/ingress/ingress_test.go
@@ -1,6 +1,7 @@
 package ingress
 
 import (
+	"net/url"
 	"testing"
 
 	"github.com/TBD54566975/ftl/backend/schema"
@@ -73,3 +74,54 @@ func TestValidation(t *testing.T) {
 		})
 	}
 }
+
+func TestParseQueryParams(t *testing.T) {
+	tests := []struct {
+		query   string
+		request obj
+		err     string
+	}{
+		{query: "", request: obj{}},
+		{query: "a=10", request: obj{"a": "10"}},
+		{query: "a=10&a=11", request: obj{"a": []string{"10", "11"}}},
+		{query: "a=10&b=11&b=12", request: obj{"a": "10", "b": []string{"11", "12"}}},
+		{query: "[a,b]=c", request: nil, err: "complex key '[a,b]' is not supported, use '@json=' instead"},
+		{query: "a=[1,2]", request: nil, err: "complex value '[1,2]' is not supported, use '@json=' instead"},
+	}
+
+	for _, test := range tests {
+		parsedQuery, err := url.ParseQuery(test.query)
+		assert.NoError(t, err)
+		actual, err := parseQueryParams(parsedQuery)
+		assert.EqualError(t, err, test.err)
+		assert.Equal(t, test.request, actual, test.query)
+	}
+}
+
+func TestParseQueryJson(t *testing.T) {
+	tests := []struct {
+		query   string
+		request obj
+		err     string
+	}{
+		{query: "@json=", request: nil, err: "failed to parse '@json' query parameter: unexpected end of JSON input"},
+		{query: "@json=10", request: nil, err: "failed to parse '@json' query parameter: json: cannot unmarshal number into Go value of type map[string]interface {}"},
+		{query: "@json=10&a=b", request: nil, err: "only '@json' parameter is allowed, but other parameters were found"},
+		{query: "@json=%7B%7D", request: obj{}},
+		{query: `@json=%7B%22a%22%3A%2010%7D`, request: obj{"a": 10.0}},
+		{query: `@json=%7B%22a%22%3A%2010%2C%20%22b%22%3A%2011%7D`, request: obj{"a": 10.0, "b": 11.0}},
+		{query: `@json=%7B%22a%22%3A%20%7B%22b%22%3A%2010%7D%7D`, request: obj{"a": obj{"b": 10.0}}},
+		{query: `@json=%7B%22a%22%3A%20%7B%22b%22%3A%2010%7D%2C%20%22c%22%3A%2011%7D`, request: obj{"a": obj{"b": 10.0}, "c": 11.0}},
+
+		// also works with non-urlencoded json
+		{query: `@json={"a": {"b": 10}, "c": 11}`, request: obj{"a": obj{"b": 10.0}, "c": 11.0}},
+	}
+
+	for _, test := range tests {
+		parsedQuery, err := url.ParseQuery(test.query)
+		assert.NoError(t, err)
+		actual, err := parseQueryParams(parsedQuery)
+		assert.EqualError(t, err, test.err)
+		assert.Equal(t, test.request, actual, test.query)
+	}
+}