Forest had the chance to make a perfect start when they were awarded an early penalty after Pervis Estupinan clumsily fouled Neco Williams.
But Jason Steele produced a big save to deny Johnson’s spot-kick and the hosts missed their chance.
Brighton took the lead in the 38th minute as they capitalised on poor handling from Keylor Navas.
The Chilean goalkeeper palmed Solly March’s shot straight out into the danger zone and Facundo Buonanotte celebrated his first Premier League start with the easiest of tap-ins.
Forest levelled deep into first-half injury time as Pascal Gross put through his own net when he tried to clear Renan Lodi’s cross at the near post, ensuring a frantic first half ended 1-1.
Forest took the lead in the 69th minute with a goal out of nowhere as Danilo closed down Moses Caicedo on the halfway line and then raced on to Awoniyi’s pass and slotted into the far corner to send the City Ground wild.
Forest made sure of the points late on when Morgan Gibbs-White converted from the spot after Lewis Dunk had handled from a corner.
Here’s how the Albion players rated at the City Ground...

9. Solly March 6
Kept going to the end. Drifted in an out of the match. It was his effort that was spilled by Navas for the Albion opener. Moved to left back after Estupinan was subbed. Long range effort on 79 minutes was well saved. Photo: GEOFF CADDICK

10. Julio Enciso 5
Saw his effort from Mitoma's fine and cross tipped over by Navas. Lively front runner but failed to make an impact in the second half against a packed Forest rear guard Photo: Clive Mason

11. Mitoma 6
Electric in the first half. Destroyed Williams for pace and skill and so dangerous. Glides past defenders with ease. Faded in the second half as Brighton struggled to get the ball to him in dangerous areas. Missed an excellent chance after the break after good play from Buonanotte Photo: Gareth Copley

12. Buonanotte 7
Showed excellent attacking instincts to score on his full Premier League debut as he latched on to poor goalkeeping from Navas. Teed up Mitoma for a great chance with a composed throughball. Moved to the right in the second half and an encouraging debut. Photo: GEOFF CADDICK

