The Norwegian striker had medicals at both the Britannia Stadium and the Hawthorns this week, but the 31-year-old has decided to join the Potters ahead of the Baggies.
Carew is due to run out of contract at the end of the season and his move to Stoke could become a permanent one in the summer if he does enough to earn a contract during his loan.
The big forward has fallen out-of-favour at Villa since the arrival of Gerard Houllier – with Darren Bent’s arrival pushing him further down the pecking order.
The striker called Houllier “disrespectful” after he was challenged to earn a new contract, with the war of words continued by the Villa boss, who told Carew to stop “living in the past”.
His arrival at Stoke could well hasten the departure of Ricardo Fuller, who looks set to leave the Potteries after Stoke accepted a £3m bid for the forward from Sunderland.
Carew will compete with the likes of Kenwyne Jones, Jonathan Walters and Tuncay for a place in the starting XI, while Mamady Sidibe could return from an Achilles injury next month to further boost boss Tony Pulis’ options in attack.
Javi Gracia said it was always going to be an uphill battle for Watford after conceding so early against Liverpool on Saturday.
Schalke 04 boss Dominico Tedesco paid tribute to goalkeeper Ralf Fahrmann after his 76th-minute penalty save proved crucial in a 1-0 win over Wolfsburg.
Mattia De Sciglio stunned that Juventus were shocked to be held to a goalless draw with SPAL on Saturday.
Sunderland have suspended midfielder Darron Gibson with immediate effect after he was charged with drink driving.
Jose Mourinho's recent bad frame of mind was still present despite Manchester United beating Brighton 2-0 at Old Trafford on Saturday, a result that puts them into the last four of the FA Cup.
Mohamed Salah continued his astounding goalscoring form on Saturday, hitting four goals as Liverpool thrashed Watford 5-0 at Anfield.