diff --git a/src/core/api/commissioner_api.cpp b/src/core/api/commissioner_api.cpp
index b08fa7416..4463d4c19 100644
--- a/src/core/api/commissioner_api.cpp
+++ b/src/core/api/commissioner_api.cpp
@@ -299,12 +299,12 @@ otError otCommissionerGeneratePSKc(otInstance *           aInstance,
                                    const otExtendedPanId *aExtPanId,
                                    uint8_t *              aPSKc)
 {
+    OT_UNUSED_VARIABLE(aInstance);
+
     otError error = OT_ERROR_DISABLED_FEATURE;
 
 #if OPENTHREAD_FTD && OPENTHREAD_ENABLE_COMMISSIONER
-    Instance &instance = *static_cast<Instance *>(aInstance);
-
-    error = instance.GetThreadNetif().GetCommissioner().GeneratePSKc(aPassPhrase, aNetworkName, *aExtPanId, aPSKc);
+    error = MeshCoP::Commissioner::GeneratePSKc(aPassPhrase, aNetworkName, *aExtPanId, aPSKc);
 #else
     OT_UNUSED_VARIABLE(aInstance);
     OT_UNUSED_VARIABLE(aPassPhrase);
diff --git a/src/core/thread/mesh_forwarder.cpp b/src/core/thread/mesh_forwarder.cpp
index 66056d0b4..8e704a393 100644
--- a/src/core/thread/mesh_forwarder.cpp
+++ b/src/core/thread/mesh_forwarder.cpp
@@ -840,19 +840,18 @@ otError MeshForwarder::SendFragment(Message &aMessage, Mac::Frame &aFrame)
 
             if (hopsLeft != Mle::kMaxRouteCost)
             {
-                hopsLeft +=
-                    netif.GetMle().GetLinkCost(netif.GetMle().GetRouterId(netif.GetMle().GetNextHop(mMeshDest)));
+                hopsLeft += netif.GetMle().GetLinkCost(Mle::Mle::GetRouterId(netif.GetMle().GetNextHop(mMeshDest)));
             }
             else
             {
                 // In case there is no route to the destination router (only link).
-                hopsLeft = netif.GetMle().GetLinkCost(netif.GetMle().GetRouterId(mMeshDest));
+                hopsLeft = netif.GetMle().GetLinkCost(Mle::Mle::GetRouterId(mMeshDest));
             }
         }
 
         // The hopsLft field MUST be incremented by one if the destination RLOC16
         // is not that of an active Router.
-        if (!netif.GetMle().IsActiveRouter(mMeshDest))
+        if (!Mle::Mle::IsActiveRouter(mMeshDest))
         {
             hopsLeft += 1;
         }
@@ -1036,7 +1035,7 @@ void MeshForwarder::HandleSentFrame(Mac::Frame &aFrame, otError aError)
         case OT_ERROR_NO_ACK:
             neighbor->IncrementLinkFailures();
 
-            if (netif.GetMle().IsActiveRouter(neighbor->GetRloc16()))
+            if (Mle::Mle::IsActiveRouter(neighbor->GetRloc16()))
             {
                 if (neighbor->GetLinkFailures() >= Mle::kFailedRouterTransmissions)
                 {
@@ -1593,7 +1592,7 @@ otError MeshForwarder::GetFramePriority(const uint8_t *     aFrame,
 
     SuccessOrExit(error = DecompressIp6Header(aFrame, aFrameLength, aMacSource, aMacDest, ip6Header, headerLength,
                                               nextHeaderCompressed));
-    aPriority = GetNetif().GetIp6().DscpToPriority(ip6Header.GetDscp());
+    aPriority = Ip6::Ip6::DscpToPriority(ip6Header.GetDscp());
     VerifyOrExit(ip6Header.GetNextHeader() == Ip6::kProtoUdp);
 
     aFrame += headerLength;
diff --git a/src/core/thread/mesh_forwarder_ftd.cpp b/src/core/thread/mesh_forwarder_ftd.cpp
index 3a0b50a62..a9a4936f6 100644
--- a/src/core/thread/mesh_forwarder_ftd.cpp
+++ b/src/core/thread/mesh_forwarder_ftd.cpp
@@ -804,7 +804,7 @@ otError MeshForwarder::UpdateIp6RouteFtd(Ip6::Header &ip6Header)
 
         if (aloc16 == Mle::kAloc16Leader)
         {
-            mMeshDest = netif.GetMle().GetRloc16(netif.GetMle().GetLeaderId());
+            mMeshDest = Mle::Mle::GetRloc16(netif.GetMle().GetLeaderId());
         }
         else if ((aloc16 >= Mle::kAloc16CommissionerStart) && (aloc16 <= Mle::kAloc16CommissionerEnd))
         {
@@ -820,18 +820,18 @@ otError MeshForwarder::UpdateIp6RouteFtd(Ip6::Header &ip6Header)
                               static_cast<uint8_t>(aloc16 & Mle::kAloc16DhcpAgentMask), agentRloc16) == OT_ERROR_NONE),
                          error = OT_ERROR_DROP);
 
-            routerId = netif.GetMle().GetRouterId(agentRloc16);
+            routerId = Mle::Mle::GetRouterId(agentRloc16);
 
             // if agent is active router or the child of the device
-            if ((netif.GetMle().IsActiveRouter(agentRloc16)) ||
-                (netif.GetMle().GetRloc16(routerId) == netif.GetMle().GetRloc16()))
+            if ((Mle::Mle::IsActiveRouter(agentRloc16)) ||
+                (Mle::Mle::GetRloc16(routerId) == netif.GetMle().GetRloc16()))
             {
                 mMeshDest = agentRloc16;
             }
             else
             {
                 // use the parent of the ED Agent as Dest
-                mMeshDest = netif.GetMle().GetRloc16(routerId);
+                mMeshDest = Mle::Mle::GetRloc16(routerId);
             }
         }
 
@@ -1179,7 +1179,7 @@ otError MeshForwarder::GetDestinationRlocByServiceAloc(uint16_t aServiceAloc, ui
 {
     otError                  error      = OT_ERROR_NONE;
     ThreadNetif &            netif      = GetNetif();
-    uint8_t                  serviceId  = netif.GetMle().GetServiceIdFromAloc(aServiceAloc);
+    uint8_t                  serviceId  = Mle::Mle::GetServiceIdFromAloc(aServiceAloc);
     NetworkData::ServiceTlv *serviceTlv = netif.GetNetworkDataLeader().FindServiceById(serviceId);
 
     if (serviceTlv != NULL)
diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 557ded179..65b8eb258 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -3173,8 +3173,8 @@ otError Mle::HandleParentResponse(const Message &aMessage, const Ip6::MessageInf
 
         case kAttachBetter:
             VerifyOrExit(leaderData.GetPartitionId() != mLeaderData.GetPartitionId());
-            VerifyOrExit(netif.GetMle().ComparePartitions(connectivity.GetActiveRouters() <= 1, leaderData,
-                                                          netif.GetMle().IsSingleton(), mLeaderData) > 0);
+            VerifyOrExit(MleRouter::ComparePartitions(connectivity.GetActiveRouters() <= 1, leaderData,
+                                                      netif.GetMle().IsSingleton(), mLeaderData) > 0);
             break;
         }
     }
@@ -3187,8 +3187,8 @@ otError Mle::HandleParentResponse(const Message &aMessage, const Ip6::MessageInf
 
         if (IsFullThreadDevice())
         {
-            compare = netif.GetMle().ComparePartitions(connectivity.GetActiveRouters() <= 1, leaderData,
-                                                       mParentIsSingleton, mParentLeaderData);
+            compare = MleRouter::ComparePartitions(connectivity.GetActiveRouters() <= 1, leaderData, mParentIsSingleton,
+                                                   mParentLeaderData);
         }
 
         // only consider partitions that are the same or better
diff --git a/src/core/thread/network_diagnostic.cpp b/src/core/thread/network_diagnostic.cpp
index 7c41c09a2..459df1c96 100644
--- a/src/core/thread/network_diagnostic.cpp
+++ b/src/core/thread/network_diagnostic.cpp
@@ -250,7 +250,7 @@ otError NetworkDiagnostic::AppendChildTable(Message &aMessage)
 
         entry.SetReserved(0);
         entry.SetTimeout(timeout + 4);
-        entry.SetChildId(netif.GetMle().GetChildId(child.GetRloc16()));
+        entry.SetChildId(Mle::Mle::GetChildId(child.GetRloc16()));
         entry.SetMode(child.GetDeviceMode());
 
         SuccessOrExit(error = aMessage.Append(&entry, sizeof(ChildTableEntry)));