diff --git a/esphome/components/json/json_util.cpp b/esphome/components/json/json_util.cpp
index 7e701af48b..f105280b23 100644
--- a/esphome/components/json/json_util.cpp
+++ b/esphome/components/json/json_util.cpp
@@ -7,6 +7,9 @@
 #ifdef USE_ESP32
 #include <esp_heap_caps.h>
 #endif
+#ifdef USE_RP2040
+#include <Arduino.h>
+#endif
 
 namespace esphome {
 namespace json {
@@ -24,6 +27,8 @@ std::string build_json(const json_build_t &f) {
   const size_t free_heap = ESP.getMaxFreeBlockSize();  // NOLINT(readability-static-accessed-through-instance)
 #elif defined(USE_ESP32)
   const size_t free_heap = heap_caps_get_largest_free_block(MALLOC_CAP_8BIT);
+#elif defined(USE_RP2040)
+  const size_t free_heap = rp2040.getFreeHeap();
 #endif
 
   size_t request_size = std::min(free_heap, (size_t) 512);
@@ -64,6 +69,8 @@ void parse_json(const std::string &data, const json_parse_t &f) {
   const size_t free_heap = ESP.getMaxFreeBlockSize();  // NOLINT(readability-static-accessed-through-instance)
 #elif defined(USE_ESP32)
   const size_t free_heap = heap_caps_get_largest_free_block(MALLOC_CAP_8BIT);
+#elif defined(USE_RP2040)
+  const size_t free_heap = rp2040.getFreeHeap();
 #endif
   bool pass = false;
   size_t request_size = std::min(free_heap, (size_t)(data.size() * 1.5));