Kelly announced the news on his own Twitter account, posting:
Crystal Palace also confirmed the move on its Twitter account:
The English defender falls victim to Brendan Rodgers' squad rebuilding process at Liverpool, which has seen eight new signings confirmed for last season's Premier League runners-up.
Kelly has failed to establish himself as either a first-choice centre-back or right-back—both positions he can comfortably fill—since making his debut for the Reds in 2008.
Liverpool's signings of Dejan Lovren and Javier Manquillo indicated Kelly would no longer be needed before Palace's bid was accepted. Lovren has already settled in nicely with a goal against Borussia Dortmund, while Rodgers' decision to snatch Manquillo on loan—a player who is four years younger than Kelly—suggests a loss of faith in the Englishman's ability.
Alberto Moreno's arrival, as reported by Ben Smith of BBC Sport, also has a knock-on effect for Kelly's career on Merseyside. Jon Flanagan will likely compete for a position at right-back now while Moreno and Jose Enrique are due to do the same on the opposite side, meaning Kelly's potential game time would look no better than the five substitute appearances he managed last season, per WhoScored.com.
Tony Pulis won't mind, though, and he will be ecstatic to welcome a potential leader into his ranks. The former Stoke boss is used to snapping up quality for minimal fees, as highlighted by his free capture of Brede Hangeland and the £900,000 paid for Fraizer Campbell this summer, per BBC Sport.
Kelly can learn plenty from Hangeland, who dominated during his six years with Fulham, before the club's relegation.
The duo's potential partnership offers power, dominance in the air and the kind of physicality Pulis' teams are usually built on. He favoured mobile wing-backs during his opening spell with Palace, with the likes of Stephen Ward bombing from deep, meaning Kelly is more likely to establish himself in the middle.
Prior to signing for the Selhurst Park side, Kelly admitted he needs a run of consistency to regain full confidence in his ability, per Doolan: "I think in terms of confidence and feeling strong I’m definitely 100 per cent, but in longer terms that takes games. I've been fit for a season now but I haven't had the games, so the run of games is vital for me this season."
Many will forget Kelly has an England appearance to his name. His career has been ravaged by injuries, however, leaving his chance of breaking into the Liverpool side slim at best. Palace have undoubtedly captured a player who has the natural ability to excel in the Premier League, if he is afforded the opportunity to gain decent minutes.
It would be typical of Pulis to improve the player's fortunes after the boss heroically led Palace to 11th last season. The experienced manager will hope a change in fortune turns Kelly into the player he has always promised to be and someone who can regularly throw his name into contention for a place in the national setup.