Bobby Zamora scored his first home goal for Albion in over 12 years since a 4-0 win over Watford in April 2003.
Derrick Williams’s opener was Bristol City’s first goal in over 8 years against Albion, a 2-0 win at Withdean in February 2007.
Sam Baldock scored his first goal in 10 games, his last strike came in the 2-1 win at Fulham in August.
Albion still remain 4 points clear at the top of the Championship table, followed by second placed Birmingham City.
Beram Kayal received a 5th yellow card of the season and will miss Albion’s next match against Preston North End.