The ITM Cup season will be the first time Donald has played in New Zealand since the 2011 Rugby World Cup final.
Donald, Waikato's fifth highest all-time points scorer, played 57 games for the province between 2004 and 2011 and is delighted to be able to contribute once more.
"I have some great memories playing for Waikato and I can't wait to pull on the jersey again and represent the province I am very passionate about. It is an exciting opportunity for me and I am looking forward to getting the ITM Cup campaign underway and running out onto Waikato Stadium once again," Donald said.
Donald is expected to be available for ITM Cup selection against Bay of Plenty next weekend.