Raised on the family farm in Pungarehu, Barrett was educated at Francis Douglas College in New Plymouth, which he left in fifth form to work on the farm.[2] He played 167 games as a forward for Taranaki between 1986 and 1999.[3] His nickname "Smiley" was coined at Taranaki from the faint smile he had during the physical on field battles.[4]
Barrett joined the Hurricanes as injury cover in 1997 and made four appearances that season, including as a flanker in their semi-final loss to the Brumbies. In 1998, Barrett was used as a lock and played 10 Super 12 games.[5]
Finishing up in New Zealand rugby in 1999, Barrett moved to County Meath, Ireland, the following year to manage a farm and he played rugby for Athlone-based club Buccaneers during the 2000–01 season.[2]
Barrett once stated "I’m off to breed some All Blacks" when asked in a match programme what he would like to do in the future.[4]
Barrett raised five sons and three daughters with wife Robyn.[6] Four of his sons have played professional rugby, eldest Kane retired early due to concussion, while Beauden, Jordie and Scott all became All Blacks.[7]