The striker is completing the formalities of his switch to Upton Park after agreeing a 117,000 euro weekly six-year contract that will make him best paid player in club's history.
The striker underwent extensive medical tests on Tuesday after agreeing a 117,000 euros-a-week, six-year contract that will make him the highest-paid player in the east London club’s history.
"We managed to bring Andy's medical forward to this evening and I am delighted to informed you that he has passed with flying colors," West Ham chairman David Gold posted on Twitter.
The Hammers had already agreed a club-record 18m euro fee with Liverpool, which will be supplemented by a potential 2.3m euros of add-ons.
West Ham only has to tie up the formalities of the deal before announcing the signing of a player that manager Sam Allardyce had prioritized during the summer window.
It represents a loss of at least 20m euros for the Merseysiders, who paid Newcastle United around 40m euros for the 24-year-old in January 2011.
Allardyce had admitted on Monday that West Ham reached an agreement with Liverpool on the fee for the big forward, who scored seven goals in 25 league games on loan at Upton Park last season.
Amid late interest from another club, believed to be Newcastle, Carroll flew back from a holiday in Florida on Monday night to agree a contract with the Hammers.