Boro took the lead in the 28th minute when Marcus Tavernier’s low shot from outside the box beat Cardiff goalkeeper Dillon Phillips.
The hosts then doubled their advantage eight minutes after half-time when Riley McGree’s effort deflected in off defender Curtis Nelson.
Boro’s win moves them up to seventh in the Championship table, two points behind Sheffield United a place ahead of them.
Here’s how each Boro player fared at the Riverside:
9. Marcus Tavernier - 8
Scored the important opener when he took on a shot from the edge of the box and possessed the quality Boro needed to help win the game. 8 Photo: Getty Images
10. Duncan Watmore - 6
Dropped deep at times to link up play and tried to drive the team forward when he received the ball in the final third. 6 Photo: Getty Images
11. Folarin Balogun - 6
Assisted the opening goal with a neat pass back to Tavernier. Didn’t find himself in many opportunities to score and was replaced on the hour mark. 6 Photo: Marc Atkins
12. Andraz Sporar - 5
(for Balogun, 61) Had a few flashes after coming on but wasn’t able to stretch the Cardiff defence. 5 Photo: Getty Images