"I'm very excited," Downing told West Ham's official website (www.whufc.com).
"It's a great opportunity for me being here, it's a great club and I'm really excited to get going.
"I'm ready and I'm fit for the first game against Cardiff City. I've played a decent few games for Liverpool in pre-season, so there will be no problems on that front.
"It's all happened quickly, but I'm really excited and hoping to play a part on Saturday."
No transfer fee was stated, but it has been reported that Liverpool will take a large loss on the deal.
Downing, capped 34 times for England, is the second Liverpool player to move to the east London club, following Andy Carroll's permanent transfer earlier in the off-season for around 15.5 million pounds, much less than the 35 million the Anfield club paid Newcastle United for the striker in January 2011.
(Reporting by Josh Reich; Editing by Rex Gowar)
