The 20-year-old, who joined the Hammers from Manchester United in January 2012, spent the 2012-13 season at St Andrew’s, where he made 30 appearances and scored three goals.
And the midfielder is keen to fight his way into contention for a regular spot at Upton Park and help the Hammers build on their 10th-place top-flight finish last term.
“Hopefully I can get an opportunity,” Morrison told West Ham’s website. “I’ve just got to carry on working hard in pre-season and show the manager what I can do.”
He added: “It [the loan spell] was really good. I think I needed the year out and I think it went well, because I enjoyed my year at Birmingham a lot,” he confirmed. “I missed West Ham a lot but it was still good in the Championship.
“It was different to the Premier League, obviously, but it was a good challenge. Lee Clark is a great manager and he helped me through a lot. He talked me through my rights and wrongs and he helped me through the season.”