The Reds bounced back well from their midweek defeat against Charlton Athletic to beat the team who went into the Championship weekend at the top of the table.
"At 1-0 I thought it would be easier but it was the opposite," said Middlesbrough boss Aitor Karanka after his side lost the lead given to them by Grant Leadbitter.
"We defended deeper and I wanted us higher. I told the players not to let Forest shoot from outside the box."
Dougie Freedman hailed what he called a 'superhuman' effort from his side to recover from a goal down to beat the team he believes will end the season as champions.
Nine points now separate Nottingham Forest from the play-off places ahead of their trip to face Leeds United at Elland Road next Saturday afternoon.