The 30-year-old joined Warrington in 2018 following a spell in rugby union with Sale Sharks and has scored 55 Super League tries for the club, leaving him third in the all-time chart with 203.
But Charnley is on the lookout for a new club after the Wolves decided against renewing his deal.
"He won’t be offered a contract for next year," said head coach Powell during his weekly press conference.
Charnley was left out against Catalans Dragons last week and is not in Warrington's squad for tomorrow's date with St Helens.
The former England international, who made his name with Wigan Warriors before switching to union, hinted at a departure on Sunday when he tagged his management company in a 'What next?' post on Twitter.
Charnley made his Super League debut for Hull KR in 2010 and went on to score five tries in as many appearances during his loan spell at Craven Park.