West Brom have previously loaned him out to Brighton & Hove Albion and Barnsley.
Wood could get game time as early as this weekend when Bristol City travel to his former club Brighton where he scored eight goals last season.
"Chris is someone I've been aware of for a while and I tried to sign him at St Johnstone," Bristol City manager Derek McInnes told the club's website.
"I'm delighted we've been able to add him to our squad."
"He's a big lad, with good feet and he's already shown himself to be a proven goalscorer in the Championship," McInnes said.
"I'm sure he will prove a valuable addition to the squad. I've seen him play a number of times; he's young, hungry and I'm sure he will enjoy his time with us."
Wood scored his first-ever professional hattrick earlier in the season in Birmingham's 3-0 win over Millwall. He also made his European debut this season scoring in his second match, a late winner against Club Brugge in a 2-1 victory in the Europa League.
- HERALD ONLINE