diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 4437617354..f0f7f4a3b1 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -867,7 +867,7 @@ message GetTimeResponse {
   option (no_delay) = true;
 
   fixed32 epoch_seconds = 1;
-  string timezone = 2;
+  string timezone = 2 [deprecated = true];  // Use parsed_timezone instead. Remove before 2026.9.0.
   ParsedTimezone parsed_timezone = 3;
 }
 
diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index 8f4aabfa21..8747e19270 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -1112,24 +1112,31 @@ void APIConnection::on_get_time_response(const GetTimeResponse &value) {
   if (homeassistant::global_homeassistant_time != nullptr) {
     homeassistant::global_homeassistant_time->set_epoch_time(value.epoch_seconds);
 #ifdef USE_TIME_TIMEZONE
-    if (!value.timezone.empty()) {
+    // Only apply if the sender provided pre-parsed timezone data.
+    // Old clients (before 2026.3.0) only send the timezone string without the parsed struct,
+    // so all parsed_timezone fields default to zero — skip to keep the codegen-configured timezone.
+    // For actual UTC (all zeros), this also skips, which is harmless since UTC is the default.
+    // Eventually the timezone string will be removed and only the struct will be sent.
+    {
       const auto &pt = value.parsed_timezone;
-      time::ParsedTimezone tz{};
-      tz.std_offset_seconds = pt.std_offset_seconds;
-      tz.dst_offset_seconds = pt.dst_offset_seconds;
-      tz.dst_start.time_seconds = pt.dst_start.time_seconds;
-      tz.dst_start.day = static_cast<uint16_t>(pt.dst_start.day);
-      tz.dst_start.type = static_cast<time::DSTRuleType>(pt.dst_start.type);
-      tz.dst_start.month = static_cast<uint8_t>(pt.dst_start.month);
-      tz.dst_start.week = static_cast<uint8_t>(pt.dst_start.week);
-      tz.dst_start.day_of_week = static_cast<uint8_t>(pt.dst_start.day_of_week);
-      tz.dst_end.time_seconds = pt.dst_end.time_seconds;
-      tz.dst_end.day = static_cast<uint16_t>(pt.dst_end.day);
-      tz.dst_end.type = static_cast<time::DSTRuleType>(pt.dst_end.type);
-      tz.dst_end.month = static_cast<uint8_t>(pt.dst_end.month);
-      tz.dst_end.week = static_cast<uint8_t>(pt.dst_end.week);
-      tz.dst_end.day_of_week = static_cast<uint8_t>(pt.dst_end.day_of_week);
-      time::set_global_tz(tz);
+      if (pt.std_offset_seconds != 0 || pt.dst_start.type != enums::DST_RULE_TYPE_NONE) {
+        time::ParsedTimezone tz{};
+        tz.std_offset_seconds = pt.std_offset_seconds;
+        tz.dst_offset_seconds = pt.dst_offset_seconds;
+        tz.dst_start.time_seconds = pt.dst_start.time_seconds;
+        tz.dst_start.day = static_cast<uint16_t>(pt.dst_start.day);
+        tz.dst_start.type = static_cast<time::DSTRuleType>(pt.dst_start.type);
+        tz.dst_start.month = static_cast<uint8_t>(pt.dst_start.month);
+        tz.dst_start.week = static_cast<uint8_t>(pt.dst_start.week);
+        tz.dst_start.day_of_week = static_cast<uint8_t>(pt.dst_start.day_of_week);
+        tz.dst_end.time_seconds = pt.dst_end.time_seconds;
+        tz.dst_end.day = static_cast<uint16_t>(pt.dst_end.day);
+        tz.dst_end.type = static_cast<time::DSTRuleType>(pt.dst_end.type);
+        tz.dst_end.month = static_cast<uint8_t>(pt.dst_end.month);
+        tz.dst_end.week = static_cast<uint8_t>(pt.dst_end.week);
+        tz.dst_end.day_of_week = static_cast<uint8_t>(pt.dst_end.day_of_week);
+        time::set_global_tz(tz);
+      }
     }
 #endif
   }
diff --git a/esphome/components/api/api_pb2.cpp b/esphome/components/api/api_pb2.cpp
index 9e74d5ddc7..3f23943b12 100644
--- a/esphome/components/api/api_pb2.cpp
+++ b/esphome/components/api/api_pb2.cpp
@@ -1007,10 +1007,6 @@ bool ParsedTimezone::decode_length(uint32_t field_id, ProtoLengthDelimited value
 }
 bool GetTimeResponse::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
-    case 2: {
-      this->timezone = StringRef(reinterpret_cast<const char *>(value.data()), value.size());
-      break;
-    }
     case 3:
       value.decode_to_message(this->parsed_timezone);
       break;
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 37ed14415c..a712be4637 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1153,12 +1153,11 @@ class ParsedTimezone final : public ProtoDecodableMessage {
 class GetTimeResponse final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 37;
-  static constexpr uint8_t ESTIMATED_SIZE = 31;
+  static constexpr uint8_t ESTIMATED_SIZE = 22;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "get_time_response"; }
 #endif
   uint32_t epoch_seconds{0};
-  StringRef timezone{};
   ParsedTimezone parsed_timezone{};
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *dump_to(DumpBuffer &out) const override;
diff --git a/esphome/components/api/api_pb2_dump.cpp b/esphome/components/api/api_pb2_dump.cpp
index 290e5fe4d2..869892c691 100644
--- a/esphome/components/api/api_pb2_dump.cpp
+++ b/esphome/components/api/api_pb2_dump.cpp
@@ -1291,7 +1291,6 @@ const char *ParsedTimezone::dump_to(DumpBuffer &out) const {
 const char *GetTimeResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, "GetTimeResponse");
   dump_field(out, "epoch_seconds", this->epoch_seconds);
-  dump_field(out, "timezone", this->timezone);
   out.append("  parsed_timezone: ");
   this->parsed_timezone.dump_to(out);
   out.append("\n");