The former Australia Sevens and Under-21 international played eight times for Taranaki in 2004 before playing three Super Rugby games for the Reds in 2005 and 10 for the Force in 2006.
He then took up a contract in France with Clermont Auvergne making 289 appearances for the club across 11 seasons during which he scored 2483 points. The club won the European Challenge Cup final in 2007 and the Top 14 title in 2010.
He followed that with three seasons for La Rochelle, scoring 421 points in 57 games between 2016-20 broken by one season with Bordeaux in which he played 23 games for 75 points.
In June 2020 he switched to coaching when joining the Ospreys as their attack coach on a three-year deal.
However, at the end of the 2021-22 season he has been granted an early finish to his contract.
"This has been a really hard decision," he said.
"With my family in New Zealand I have decided to rejoin them there."
Ospreys head coach Toby Booth said: "We are disappointed to see Brock leave but totally understand his reasons for deciding to put his family first.
"His honesty, integrity and deep knowledge of the game have been a huge benefit to myself, his fellow coaches and the players. I look forward to seeing him continue his coaching career in New Zealand."