Powell made 21 appearances for Wasps this term, scoring one try in the process, but will now turn his attentions to propelling Sale up the Aviva Premiership table after they finished third-from-bottom this season.
"It has been a tough couple of weeks for me but that has gone now and I am looking forward to a new challenge at Sale," Powell told Telegraph Sport.
"There was a bit of interest from other clubs but I have been really impressed with what I have seen at Sale."
The 29-year-old was restricted to just one appearance during this year's RBS 6 Nations, lasting just over half an hour in Wales' opener against England before injury put an end to his campaign.
Powell has never played in a World Cup but this move certainly moves him a step closer to fulfilling his dream in New Zealand later this year, despite being left out of Warren Gatland's squad to face the Barbarians on June 4.