Boro fell behind to Sean Morrison's header in the first half but dominated possession and created the better chances.
Eventually their pressure paid off as Paddy McNair converted an 82-minute equaliser at the far post following Chuba Akpom’s flick on.
Akpom came off the bench along with Neeskens Kebano, Djed Spence and Marvin Johnson, and all the substitutes made an impact.
January signing Nathanial Mendez-Laing also made his first Boro start and operated on the right against his former side.
Despite the late leveller, Boro drifted further away from the play-off pack and are now five points off the top six.
Manager Neil Warnock will now hope Boro can keep pressure on the teams above them when his side face Coventry and Swansea away from home.
Here’s how his side fared:
1. Marcus Bettinelli - 6
Made an early save to keep out Harry Wilson’s free-kick. Cardiff’s only other effort on target was the goal. 6 Photo: Alex Burstow
2. Anfernee Dijksteel - 7
Man marked Josh Murphy until the Cardiff forward was withdrawn in the second half. Assured at the back. 7 Photo: George Wood
3. Grant Hall - 7
Kept in-form striker Kieffer Moore quiet as he swept up danger at the back. 7 Photo: Stu Forster
4. Dael Fry - 7
Almost caught out when his backpass was cleared by Bettinelli but was comfortable for most of the match. 7 Photo: Getty Images