Quinnell confirmed he had lost his fight to play again before he retires officially at the end of the current campaign.
The Scarlets legend was hoping to get back on the field during the last weeks of this season but a hand injury has forced him to call it a day earlier than he would have wanted.
The 32-year-old explained: "It's just unfortunate - and it's ironic that the thing that finished my career was my hand rather than my knees.
"It's a question now of looking to new horizons and getting on with things.
"I've been lucky with what I have had and achieved in rugby, and you have to be thankful for that.
"I wanted to play again but I would need a soft cast on the hand which wouldn't be allowed in a competitive game."
Quinnell has not played since he was injured during the Scarlets' Celtic League clash against the Blues last November 7.
Since then knee injuries and ultimately the hand problem have kept him sidelined.
Quinnell, capped by Wales 52 times, made his debut for Llanelli as an 18-year-old in 1990 and went on to play for the club side 146 times, which came in two spells.
He was lured to rugby league with Wigan in 1994 after helping Wales to the Five Nations championship.
After union lifted its ban on rugby league players he was signed by Richmond before returning to Stradey in 1998.
After Llanelli were transformed into the Scarlets Quinnell played 59 times for the regional side.
Quinnell was twice a Lion, taking part in the 1997 and 2001 tours to South Africa and Australia respectively.