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:
1. Luke Daniels - 7
Made a few comfortable saves and collected some crosses from corners but wasn’t overly tested. 7 Photo: Stu Forster
2. Anfernee Dijksteel - 7
Tucked in when he needed to on the right side of Boro’s defence as the hosts conceded few chances. 7 Photo: Getty Images
3. Sol Bamba - 8
Commanding in the air and was quick to thwart Cardiff’s attacking players when the ball was played forward. 8 Photo: Stu Forster
4. Paddy McNair - 7
Was caught out by a couple of passes played in behind him but saw out most of his defensive duties. Showed composure in possession. 7 Photo: Robbie Jay Barratt - AMA