In aspects of packet segmentation and reassembly for mesh networks, a source node in a mesh network segments an access protocol data unit (PDU) into a set of segments that are concatenated with a segment transport header and transmitted over the mesh network in segmented access messages to a destination node. The destination node allocates memory to store the content of the access PDU based on a segment total field in the segment transport header, and stores each received segment at the appropriate offset in the allocated memory, based on a value of a segment offset filed in each segmented access message. The destination node transmits a segment acknowledgement message including a segment acknowledgement field indicating which of the multiple segments have been received by the destination node.