diff --git a/src/core/meshcop/dataset_manager_ftd.cpp b/src/core/meshcop/dataset_manager_ftd.cpp
index 8f5916220..d0b188498 100644
--- a/src/core/meshcop/dataset_manager_ftd.cpp
+++ b/src/core/meshcop/dataset_manager_ftd.cpp
@@ -375,7 +375,7 @@ void PendingDatasetManager::ApplyActiveDataset(Dataset &aDataset)
 
     SuccessOrExit(aDataset.Read<ActiveTimestampTlv>(activeTimestamp));
     SuccessOrExit(aDataset.Write<PendingTimestampTlv>(activeTimestamp));
-    SuccessOrExit(aDataset.Write<DelayTimerTlv>(GetDelayTimerMinimal()));
+    SuccessOrExit(aDataset.Write<DelayTimerTlv>(DelayTimerTlv::kDefaultDelay));
 
     IgnoreError(DatasetManager::Save(aDataset));
     StartDelayTimer(aDataset);
diff --git a/tests/scripts/expect/cli-dataset-mgmt-delay-floor.exp b/tests/scripts/expect/cli-dataset-mgmt-delay-floor.exp
new file mode 100755
index 000000000..aaa1a6b9d
--- /dev/null
+++ b/tests/scripts/expect/cli-dataset-mgmt-delay-floor.exp
@@ -0,0 +1,76 @@
+#!/usr/bin/expect -f
+#
+#  Copyright (c) 2026, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+# Verifies that a MGMT_ACTIVE_SET request which changes the Network Key is
+# applied through the Pending Dataset with the default delay
+# (OPENTHREAD_CONFIG_TMF_PENDING_DATASET_DEFAULT_DELAY, 300s), so a key
+# change cannot take effect faster than the default delay. An unexpected
+# Delay Timer TLV in the Active Dataset is ignored, so the outcome is the
+# same whether the request omits the TLV or carries one.
+
+source "tests/scripts/expect/_common.exp"
+
+spawn_node 1
+setup_leader
+
+# Case A: key-changing MGMT_ACTIVE_SET without a Delay Timer TLV.
+
+send "dataset mgmtsetcommand active activetimestamp 99999998 networkkey 00112233445566778899aabbccddee0a\n"
+expect_line "Done"
+
+sleep 2
+
+send "dataset pending\n"
+expect -re {Delay: (\d+)}
+set delay $expect_out(1,string)
+expect -re {Network Key: 00112233445566778899aabbccddee0a}
+expect_line "Done"
+
+if {$delay < 250000} {
+    fail "Pending delay for key change (no Delay Timer TLV) is $delay ms, expected the 300s default delay"
+}
+
+# Case B: key-changing MGMT_ACTIVE_SET with a short explicit Delay Timer TLV.
+
+send "dataset mgmtsetcommand active activetimestamp 99999999 networkkey 00112233445566778899aabbccddee0b delaytimer 5000\n"
+expect_line "Done"
+
+sleep 2
+
+send "dataset pending\n"
+expect -re {Delay: (\d+)}
+set delay $expect_out(1,string)
+expect -re {Network Key: 00112233445566778899aabbccddee0b}
+expect_line "Done"
+
+if {$delay < 250000} {
+    fail "Pending delay for key change (explicit 5s Delay Timer TLV) is $delay ms, expected the 300s default delay"
+}
+
+dispose_all