Justin Marshall, the most-capped All Blacks halfback, has confirmed his rugby retirement and will return home to launch a broadcasting career.

Marshall, 36, said the current season would be his last as he prepares to play for Saracens in the English Premiership semifinal against Northampton this weekend.

The 81-test halfback plans to return to New Zealand for a role with Sky Sport in June.

"I have given a lot to the game over the past 17 seasons, but rugby has given me much, much more," Marshall said on the Saracens website.

"When I was 19, I was in danger of going off the rails but I was given a chance to move to Christchurch and play for Canterbury. Later that year, I was picked for the All Blacks and this incredible journey began. I have been so fortunate to make so many friends in this game, all around the world."

Marshall played in the 1999 and 2003 World Cups, and remains the third most-capped All Black, in between Mils Muliaina (82 tests) and Richie McCaw (80 tests).

He played 105 Super rugby matches for the Crusaders before moving to the northern hemisphere in 2005. He played for Leeds, the Ospreys, Montpelier and, for the past 18 months, Saracens.

"It has never been dull, and I have to thank my wife Nicolle, and my children for supporting me during this period. My career has made massive demands on them, and now we're all looking forward to going home to New Zealand and settling into something like a normal family life," Marshall said.

"I just feel immensely grateful to all the talented players and coaches who have made my career so enjoyable and memorable."