diff --git a/src/core/thread/network_diagnostic.cpp b/src/core/thread/network_diagnostic.cpp
index bbb305208..6c1789049 100644
--- a/src/core/thread/network_diagnostic.cpp
+++ b/src/core/thread/network_diagnostic.cpp
@@ -144,14 +144,14 @@ exit:
 #if OPENTHREAD_CONFIG_BLE_TCAT_ENABLE
 Error Server::AppendChildTableAsChildTlvs(Message &aMessage)
 {
-    Error    error = kErrorNone;
-    ChildTlv childTlv;
+    Error         error = kErrorNone;
+    ChildTlvValue childTlvValue;
 
     for (Child &child : Get<ChildTable>().Iterate(Child::kInStateValid))
     {
-        childTlv.InitFrom(child);
+        childTlvValue.InitFrom(child);
 
-        SuccessOrExit(error = childTlv.AppendTo(aMessage));
+        SuccessOrExit(error = Tlv::Append<ChildTlv>(aMessage, childTlvValue));
     }
 
     error = Tlv::AppendEmpty<ChildTlv>(aMessage);
@@ -736,14 +736,14 @@ exit:
 
 Error Server::AppendChildTableAsChildTlvs(Coap::Message *&aAnswer, AnswerInfo &aInfo)
 {
-    Error    error = kErrorNone;
-    ChildTlv childTlv;
+    Error         error = kErrorNone;
+    ChildTlvValue childTlvValue;
 
     for (Child &child : Get<ChildTable>().Iterate(Child::kInStateValid))
     {
-        childTlv.InitFrom(child);
+        childTlvValue.InitFrom(child);
 
-        SuccessOrExit(error = childTlv.AppendTo(*aAnswer));
+        SuccessOrExit(error = Tlv::Append<ChildTlv>(*aAnswer, childTlvValue));
         SuccessOrExit(error = CheckAnswerLength(aAnswer, aInfo));
     }
 
diff --git a/src/core/thread/network_diagnostic_tlvs.cpp b/src/core/thread/network_diagnostic_tlvs.cpp
index 1ed36f73b..1ce08a8f0 100644
--- a/src/core/thread/network_diagnostic_tlvs.cpp
+++ b/src/core/thread/network_diagnostic_tlvs.cpp
@@ -136,15 +136,12 @@ void EnhancedRouteTlvEntry::Parse(ParseInfo &aParseInfo) const
 #if OPENTHREAD_FTD
 
 //---------------------------------------------------------------------------------------------------------------------
-// ChildTlv
+// ChildTlvValue
 
-void ChildTlv::InitFrom(const Child &aChild)
+void ChildTlvValue::InitFrom(const Child &aChild)
 {
     Clear();
 
-    SetType(kChild);
-    SetLength(sizeof(*this) - sizeof(Tlv));
-
     mFlags |= aChild.IsRxOnWhenIdle() ? kFlagsRxOnWhenIdle : 0;
     mFlags |= aChild.IsFullThreadDevice() ? kFlagsFtd : 0;
     mFlags |= (aChild.GetNetworkDataType() == NetworkData::kFullSet) ? kFlagsFullNetdta : 0;
diff --git a/src/core/thread/network_diagnostic_tlvs.hpp b/src/core/thread/network_diagnostic_tlvs.hpp
index d0c78d1cc..0264da664 100644
--- a/src/core/thread/network_diagnostic_tlvs.hpp
+++ b/src/core/thread/network_diagnostic_tlvs.hpp
@@ -451,7 +451,7 @@ typedef TlvInfo<Tlv::kTypeList> TypeListTlv;
  * Implements Child TLV generation and parsing.
  */
 OT_TOOL_PACKED_BEGIN
-class ChildTlv : public Tlv, public TlvInfo<Tlv::kChild>, public Clearable<ChildTlv>
+class ChildTlvValue : public Clearable<ChildTlvValue>
 {
 public:
     static constexpr uint8_t kFlagsRxOnWhenIdle = 1 << 7; ///< Device mode - Rx-on when idle.
@@ -612,6 +612,11 @@ private:
     uint8_t         mCslChannel;          // CSL channel.
 } OT_TOOL_PACKED_END;
 
+/**
+ * Defines Child TLV constants and types.
+ */
+typedef SimpleTlvInfo<Tlv::kChild, ChildTlvValue> ChildTlv;
+
 /**
  * Implements Child IPv6 Address List Value generation and parsing.
  *
diff --git a/src/core/utils/mesh_diag.cpp b/src/core/utils/mesh_diag.cpp
index cb4283ce7..ce57cec01 100644
--- a/src/core/utils/mesh_diag.cpp
+++ b/src/core/utils/mesh_diag.cpp
@@ -285,21 +285,20 @@ exit:
 
 bool MeshDiag::ProcessChildTableAnswer(Coap::Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
 {
-    bool       didProcess = false;
-    ChildTlv   childTlv;
-    ChildEntry entry;
-    uint16_t   offset;
+    bool          didProcess = false;
+    Tlv::Info     tlvInfo;
+    ChildTlvValue childTlvValue;
+    ChildEntry    entry;
 
     SuccessOrExit(ProcessMessage(aMessage, aMessageInfo, mQueryChildTable.mRouterRloc16));
 
     while (true)
     {
-        SuccessOrExit(Tlv::FindTlv(aMessage, childTlv, offset));
-        VerifyOrExit(!childTlv.IsExtended());
+        SuccessOrExit(tlvInfo.FindIn(aMessage, ChildTlv::kType));
 
         didProcess = true;
 
-        if (childTlv.GetLength() == 0)
+        if (tlvInfo.GetLength() == 0)
         {
             // We reached end of the list.
             mState = kStateIdle;
@@ -308,17 +307,16 @@ bool MeshDiag::ProcessChildTableAnswer(Coap::Message &aMessage, const Ip6::Messa
             ExitNow();
         }
 
-        VerifyOrExit(childTlv.GetLength() >= sizeof(ChildTlv) - sizeof(Tlv));
-        IgnoreError(aMessage.Read(offset, childTlv));
+        SuccessOrExit(tlvInfo.Read<ChildTlv>(aMessage, childTlvValue));
 
-        entry.SetFrom(childTlv);
+        entry.SetFrom(childTlvValue);
         mQueryChildTable.mCallback.InvokeIfSet(kErrorPending, &entry);
 
         // Make sure query operation is not canceled from the
         // callback.
         VerifyOrExit(mState == kStateQueryChildTable);
 
-        aMessage.SetOffset(static_cast<uint16_t>(offset + childTlv.GetSize()));
+        aMessage.SetOffset(tlvInfo.GetTlvOffsetRange().GetEndOffset());
     }
 
 exit:
@@ -581,29 +579,29 @@ exit:
 //---------------------------------------------------------------------------------------------------------------------
 // MeshDiag::ChildEntry
 
-void MeshDiag::ChildEntry::SetFrom(const ChildTlv &aChildTlv)
+void MeshDiag::ChildEntry::SetFrom(const ChildTlvValue &aChildTlvValue)
 {
-    mRxOnWhenIdle        = (aChildTlv.GetFlags() & ChildTlv::kFlagsRxOnWhenIdle);
-    mDeviceTypeFtd       = (aChildTlv.GetFlags() & ChildTlv::kFlagsFtd);
-    mFullNetData         = (aChildTlv.GetFlags() & ChildTlv::kFlagsFullNetdta);
-    mCslSynchronized     = (aChildTlv.GetFlags() & ChildTlv::kFlagsCslSync);
-    mSupportsErrRate     = (aChildTlv.GetFlags() & ChildTlv::kFlagsTrackErrRate);
-    mRloc16              = aChildTlv.GetRloc16();
-    mExtAddress          = aChildTlv.GetExtAddress();
-    mVersion             = aChildTlv.GetVersion();
-    mTimeout             = aChildTlv.GetTimeout();
-    mAge                 = aChildTlv.GetAge();
-    mConnectionTime      = aChildTlv.GetConnectionTime();
-    mSupervisionInterval = aChildTlv.GetSupervisionInterval();
-    mLinkMargin          = aChildTlv.GetLinkMargin();
-    mAverageRssi         = aChildTlv.GetAverageRssi();
-    mLastRssi            = aChildTlv.GetLastRssi();
-    mFrameErrorRate      = aChildTlv.GetFrameErrorRate();
-    mMessageErrorRate    = aChildTlv.GetMessageErrorRate();
-    mQueuedMessageCount  = aChildTlv.GetQueuedMessageCount();
-    mCslPeriod           = aChildTlv.GetCslPeriod();
-    mCslTimeout          = aChildTlv.GetCslTimeout();
-    mCslChannel          = aChildTlv.GetCslChannel();
+    mRxOnWhenIdle        = (aChildTlvValue.GetFlags() & ChildTlvValue::kFlagsRxOnWhenIdle);
+    mDeviceTypeFtd       = (aChildTlvValue.GetFlags() & ChildTlvValue::kFlagsFtd);
+    mFullNetData         = (aChildTlvValue.GetFlags() & ChildTlvValue::kFlagsFullNetdta);
+    mCslSynchronized     = (aChildTlvValue.GetFlags() & ChildTlvValue::kFlagsCslSync);
+    mSupportsErrRate     = (aChildTlvValue.GetFlags() & ChildTlvValue::kFlagsTrackErrRate);
+    mRloc16              = aChildTlvValue.GetRloc16();
+    mExtAddress          = aChildTlvValue.GetExtAddress();
+    mVersion             = aChildTlvValue.GetVersion();
+    mTimeout             = aChildTlvValue.GetTimeout();
+    mAge                 = aChildTlvValue.GetAge();
+    mConnectionTime      = aChildTlvValue.GetConnectionTime();
+    mSupervisionInterval = aChildTlvValue.GetSupervisionInterval();
+    mLinkMargin          = aChildTlvValue.GetLinkMargin();
+    mAverageRssi         = aChildTlvValue.GetAverageRssi();
+    mLastRssi            = aChildTlvValue.GetLastRssi();
+    mFrameErrorRate      = aChildTlvValue.GetFrameErrorRate();
+    mMessageErrorRate    = aChildTlvValue.GetMessageErrorRate();
+    mQueuedMessageCount  = aChildTlvValue.GetQueuedMessageCount();
+    mCslPeriod           = aChildTlvValue.GetCslPeriod();
+    mCslTimeout          = aChildTlvValue.GetCslTimeout();
+    mCslChannel          = aChildTlvValue.GetCslChannel();
 }
 
 //---------------------------------------------------------------------------------------------------------------------
diff --git a/src/core/utils/mesh_diag.hpp b/src/core/utils/mesh_diag.hpp
index d20fd40d9..35a142738 100644
--- a/src/core/utils/mesh_diag.hpp
+++ b/src/core/utils/mesh_diag.hpp
@@ -286,7 +286,7 @@ private:
         friend class MeshDiag;
 
     private:
-        void SetFrom(const NetworkDiagnostic::ChildTlv &aChildTlv);
+        void SetFrom(const NetworkDiagnostic::ChildTlvValue &aChildTlvValue);
     };
 
     class RouterNeighborEntry : public otMeshDiagRouterNeighborEntry