An own goal from visiting defender Jordan Storey and a second-half header from Marcus Tavernier gave Boro all three points, while there was also a controversial red card for Preston’s Alan Browne.
The midfielder was dismissed in the 36th minute following a tussle with Sam Morsy, a decision which North End boss Alex Neil described as ‘very poor’ and altered the course of the game.
Boro were 1-0 up at the time but coming under pressure, yet they looked comfortable playing against 10 men in the second half.
The result moved the Teessiders up a place to eighth in the Championship table and five points off the play-off places.
That gap could widen again, though, with promotion rivals Reading and Barnsley set to play on Wednesday.
Here’s how the hosts fared at the Riverside:
. MIDDLESBROUGH, ENGLAND - MARCH 16: Marcus Tavernier of Middlesbrough celebrates with Marc Bola and team mates after scoring their side's second goal during the Sky Bet Championship match between Middlesbrough and Preston North End at Riverside Stadium on March 16, 2021 in Middlesbrough, England. Sporting stadiums around the UK remain under strict restrictions due to the Coronavirus Pandemic as Government social distancing laws prohibit fans inside venues resulting in games being played behind closed doors. (Photo by Stu Forster/Getty Images)
Marcus Tavernier of Middlesbrough celebrates with Marc Bola and team mates after scoring their side's second goal against Preston. Photo: Stu Forster
. Marcus Bettinelli - 6
Spilled an early cross from Paul Gallagher. Didn’t have much to do in the second half. 6 Photo: Alex Burstow
. Darnell Fisher - 7
Tried to get forward from right-back in the first half but was forced to do more defending before Preston were reduced to 10 men. 7 Photo: George Wood
. Grant Hall - 8
Kept Preston striker Ched Evans under wraps in the first half and was comfortable stepping out from the back. Has consistently impressed since returning from injury. 8 Photo: Stu Forster
. Dael Fry - 8
Another solid display alongside Hall at the back. Helped Bettinelli out of trouble in the first half. 8 Photo: Getty Images
1. Marcus Bettinelli - 6
Spilled an early cross from Paul Gallagher. Didn’t have much to do in the second half. 6 Photo: Alex Burstow
2. Darnell Fisher - 7
Tried to get forward from right-back in the first half but was forced to do more defending before Preston were reduced to 10 men. 7 Photo: George Wood
3. Grant Hall - 8
Kept Preston striker Ched Evans under wraps in the first half and was comfortable stepping out from the back. Has consistently impressed since returning from injury. 8 Photo: Stu Forster
4. Dael Fry - 8
Another solid display alongside Hall at the back. Helped Bettinelli out of trouble in the first half. 8 Photo: Getty Images