Parsons,34, has played 115 games for the Auckland based franchise and sits behind only Keven Mealaumu, Jerome Kaino and Tony Woodcock on the list of most capped players for the franchise.
He made his debut against the Highlanders in 2012 and play 106 matches for North Harbour.
Parsons made his international debut against Scotland at Murrayfield in 2014 and was recalled for a second test against Australia in Wellington two years later.
Parsons, said he's retiring on medical advice, after being out of the game for several months due to a head injury.
