Borriello joined West Ham on loan from Roma until the end of the season earlier this week as manager Sam Allardyce adds to a squad that is fighting relegation.
The 31-year-old attacker has struggled for first-team football at Roma, making just 11 Serie A appearances and scoring one goal this season, and says he is eager for the chance to prove himself in a new league.
"I was given the opportunity to move in the summer and I was looking to come over to England and the Premier League, but I decided to stay at Roma at that time," Borriello told the club's official website.
"However, when the opportunity arose to join West Ham in this transfer window, I was very happy to make the move.
"I can't wait to start playing in the Premier League - I know the fans are very passionate and I'm very excited by the challenge.
"I know it is a very tough league, but I am very much looking forward to testing myself here.
"Serie A and the Premier League are two different leagues. The Italian league is a bit more tactical, whereas the English league is maybe more physical.
"However, the ball is round in both countries, so if you are good player you can play in any league in the world."
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