diff --git a/esphome/components/syslog/esphome_syslog.cpp b/esphome/components/syslog/esphome_syslog.cpp
index 94854d5aba..83ad6b2720 100644
--- a/esphome/components/syslog/esphome_syslog.cpp
+++ b/esphome/components/syslog/esphome_syslog.cpp
@@ -41,31 +41,39 @@ void Syslog::log_(const int level, const char *tag, const char *message, size_t
     len -= 11;
   }
 
-  // Build syslog packet on stack - 508 is max UDP packet size
+  // Build syslog packet on stack (508 bytes chosen as practical limit for syslog over UDP)
   char packet[508];
   size_t offset = 0;
+  size_t remaining = sizeof(packet);
 
-  // Write PRI
-  int ret = snprintf(packet, sizeof(packet), "<%d>", pri);
-  if (ret > 0)
-    offset = ret;
+  // Write PRI - abort if this fails as packet would be malformed
+  int ret = snprintf(packet, remaining, "<%d>", pri);
+  if (ret <= 0 || static_cast<size_t>(ret) >= remaining) {
+    return;
+  }
+  offset = ret;
+  remaining -= ret;
 
-  // Write timestamp directly into packet (RFC 5424: use "-" if time not valid)
+  // Write timestamp directly into packet (RFC 5424: use "-" if time not valid or strftime fails)
   auto now = this->time_->now();
-  if (now.is_valid()) {
-    offset += now.strftime(packet + offset, sizeof(packet) - offset, "%b %e %H:%M:%S");
-  } else {
+  size_t ts_written = now.is_valid() ? now.strftime(packet + offset, remaining, "%b %e %H:%M:%S") : 0;
+  if (ts_written > 0) {
+    offset += ts_written;
+    remaining -= ts_written;
+  } else if (remaining > 0) {
     packet[offset++] = '-';
+    remaining--;
   }
 
   // Write hostname, tag, and message
-  ret = snprintf(packet + offset, sizeof(packet) - offset, " %s %s: %.*s", App.get_name().c_str(), tag, (int) len,
-                 message);
-  if (ret > 0)
-    offset += ret;
+  ret = snprintf(packet + offset, remaining, " %s %s: %.*s", App.get_name().c_str(), tag, (int) len, message);
+  if (ret > 0) {
+    // snprintf returns chars that would be written; clamp to actual buffer space
+    offset += std::min(static_cast<size_t>(ret), remaining > 0 ? remaining - 1 : 0);
+  }
 
   if (offset > 0) {
-    this->parent_->send_packet(reinterpret_cast<const uint8_t *>(packet), std::min(offset, sizeof(packet) - 1));
+    this->parent_->send_packet(reinterpret_cast<const uint8_t *>(packet), offset);
   }
 }
 
diff --git a/tests/integration/fixtures/syslog.yaml b/tests/integration/fixtures/syslog.yaml
index fee00eb8ff..df376087e3 100644
--- a/tests/integration/fixtures/syslog.yaml
+++ b/tests/integration/fixtures/syslog.yaml
@@ -16,6 +16,11 @@ api:
               "DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD"
               "EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE"
               "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF");
+    - service: log_short_message
+      then:
+        - lambda: |-
+            // Log a short message that should arrive complete (not truncated)
+            ESP_LOGI("shorttest", "BEGIN|SHORT_MESSAGE_CONTENT|FINISH");
 
 logger:
   level: DEBUG
diff --git a/tests/integration/test_syslog.py b/tests/integration/test_syslog.py
index 552dbc610e..b31a19392c 100644
--- a/tests/integration/test_syslog.py
+++ b/tests/integration/test_syslog.py
@@ -33,7 +33,7 @@ class ParsedSyslogMessage(TypedDict):
 # Example: <134>Dec 20 14:30:45 syslog-test app: [D][app:029]: Running...
 SYSLOG_PATTERN = re.compile(
     r"<(\d+)>"  # PRI (priority = facility * 8 + severity)
-    r"(\S+ +\d+ \d+:\d+:\d+|-)"  # TIMESTAMP (BSD format or NILVALUE "-")
+    r"(\S+ +\d+ \d+:\d+:\d+|-)"  # TIMESTAMP (BSD-style "%b %e %H:%M:%S", e.g. "Dec 20 14:30:45", or NILVALUE "-")
     r" (\S+)"  # HOSTNAME
     r" (\S+):"  # TAG
     r" (.*)"  # MESSAGE
@@ -258,3 +258,27 @@ async def test_syslog(
             assert "|END" not in trunc_msg, (
                 "Message should be truncated before END marker"
             )
+
+            # Test short message - should arrive complete (not truncated)
+            short_service = next(
+                (s for s in services if s.name == "log_short_message"), None
+            )
+            assert short_service is not None, "log_short_message service not found"
+
+            await client.execute_service(short_service, {})
+
+            try:
+                short_msg = await receiver.wait_for_pattern(r"shorttest.*BEGIN\|")
+            except TimeoutError:
+                pytest.fail(
+                    f"Short test message not received. Got: {receiver.messages[-10:]}"
+                )
+
+            # Verify short message arrived complete with both markers
+            assert "BEGIN|" in short_msg, "Short message missing BEGIN marker"
+            assert "|FINISH" in short_msg, (
+                f"Short message truncated unexpectedly: {short_msg}"
+            )
+            assert "SHORT_MESSAGE_CONTENT" in short_msg, (
+                f"Short message content missing: {short_msg}"
+            )