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:
5. Isaiah Jones - 7
Looked more threatening in the second half when he was able to receive the ball in more advanced positions on the right. 7 Photo: Getty Images
6. Marc Bola - 7
Saw more of the ball in the second half on the left and delivered a few inviting crosses into the box. 7 Photo: Getty Images
7. Jonny Howson - 8
Another influential display. Positioned himself well to receive loose balls. Charged through midfield before setting up McGree for Boro’s second. 8 Photo: Robbie Jay Barratt - AMA
8. Riley McGree - 7
Grew into the game and gained more confidence with his passing. Got on the scoresheet after his effort took a deflection. 7 Photo: Getty Images