The Senegal international had the chance to link up with Harry Redknapp at Southampton after a £1.5 million bid was accepted.
But he spurned the opportunity to re-join his former manager at Portsmouth to complete a move to The Hawthorns on a three-year deal.
The striker was restricted to just 19 league starts during an injury hit season at Fratton Park but still scored four goals.
Kamara said: "I am very, very pleased to join West Brom. I had a chance to join Southampton but decided on West Brom because it is a Premiership club.
"I was impressed with the attitude at West Brom, especially when I played here on the final day of last season.
"Most of all I was impressed with Bryan Robson and the chairman because they were very keen to bring me to The Hawthorns.
"I'm just looking forward to showing my talents and hopefully the goals will come to help establish West Brom as a Premiership club."