Frank who is 35 is playing for English club Northampton and is one of 21 players to have lifted the World Cup on two occasions.
"I've loved my journey in rugby; from playing back home in New Zealand, to representing the All Blacks alongside my brother, and then coming over here to experience the challenge of the English Premiership," he told the club website.
He has made 37 Northampton appearances since signing in 2018 and said his younger brother
Owen will "continue to play on" for the club, having himself arrived at Franklin's Gardens last year.
