The Black Cats took the lead in the 17th minute when Jobe Bellingham converted from a corner, after Nazariy Rusyn flicked the ball on.
Birmingham drew level in the 30th minute, though, when Jay Stansfield set up Koji Miyoshi to make it 1-1 at the half-time interval.
Sunderland retook the lead after an own goal, before substitute Adil Aouchiche secured the points with his first goal for the club 14 minutes from time.
Here, though, we take look at the best photos of Sunderland fans throughout the day:
1. Sunderland fans
Sunderland beat Birmingham 3-1 at the Stadium of Light – and our cameras were in attendance to capture the action. Photo: Frank Reid
2. Sunderland fans
Sunderland beat Birmingham 3-1 at the Stadium of Light – and our cameras were in attendance to capture the action. Photo: Frank Reid
3. Sunderland fans
Sunderland beat Birmingham 3-1 at the Stadium of Light – and our cameras were in attendance to capture the action. Photo: Frank Reid
4. Sunderland fans
Sunderland beat Birmingham 3-1 at the Stadium of Light – and our cameras were in attendance to capture the action. Photo: Frank Reid