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: