Forest's away woes continued as they suffered another setback to their automatic promotion bid.
The pre-season title favourites have now taken only two points from their last six matches away from the City Ground.
Brighton came from behind in the second half to secure a victory which moved them into the top half of the table.
To make matters worse for Forest, they will be without star striker Nathan Tyson for the next three matches after he received a straight red card from referee Andy Woolmer for violent conduct.
Tyson was sent off in the 52nd minute for raising an arm as he tussled with Brighton defender Adam El-Abd.
The offence was spotted by a linesman and Woolmer had no hesitation in giving the former Wycombe marksman his marching orders.
Forest made light of losing Tyson at first by taking the lead three minutes later.
Jack Lester ended a weaving run from close to the corner flag with a left-foot shot which found the net via a deflection.
Brighton equalised in the 72nd minute when John Curtis was penalised for wrapping his arms around substitute Nathan Elder.
Skipper Dean Hammond drove the resulting free-kick low and hard past Forest keeper Paul Smith for his 11th goal of the season.
It ended a home goal drought for Brighton spanning more than six-and-a-half hours after Hammond scored their first goal for an even longer period, home or away, to launch the 4-1 victory at Leyton Orient in midweek.
Things got even better for Brighton a minute later as Nick Ward struck his first goal for the club.
The Australian midfielder, on-loan from QPR until the end of the season, saw his first shot blocked by Smith but he slotted the rebound to complete Brighton's comeback.
The Seagulls were grateful to goalkeeper Michels Kuipers for preserving their lead as he carried on despite suffering a groin injury in the early stages which restricted his kicking.
Kuipers, having already denied Lester and Tyson in the first half, came to the rescue again with a smart double save with 12 minutes left.
He palmed away a 25-yard piledriver from David Prutton and moments later blocked a shot from substitute Junior Agogo.
The pre-season title favourites have now taken only two points from their last six matches away from the City Ground.
Brighton came from behind in the second half to secure a victory which moved them into the top half of the table.
To make matters worse for Forest, they will be without star striker Nathan Tyson for the next three matches after he received a straight red card from referee Andy Woolmer for violent conduct.
Tyson was sent off in the 52nd minute for raising an arm as he tussled with Brighton defender Adam El-Abd.
The offence was spotted by a linesman and Woolmer had no hesitation in giving the former Wycombe marksman his marching orders.
Forest made light of losing Tyson at first by taking the lead three minutes later.
Jack Lester ended a weaving run from close to the corner flag with a left-foot shot which found the net via a deflection.
Brighton equalised in the 72nd minute when John Curtis was penalised for wrapping his arms around substitute Nathan Elder.
Skipper Dean Hammond drove the resulting free-kick low and hard past Forest keeper Paul Smith for his 11th goal of the season.
It ended a home goal drought for Brighton spanning more than six-and-a-half hours after Hammond scored their first goal for an even longer period, home or away, to launch the 4-1 victory at Leyton Orient in midweek.
Things got even better for Brighton a minute later as Nick Ward struck his first goal for the club.
The Australian midfielder, on-loan from QPR until the end of the season, saw his first shot blocked by Smith but he slotted the rebound to complete Brighton's comeback.
The Seagulls were grateful to goalkeeper Michels Kuipers for preserving their lead as he carried on despite suffering a groin injury in the early stages which restricted his kicking.
Kuipers, having already denied Lester and Tyson in the first half, came to the rescue again with a smart double save with 12 minutes left.
He palmed away a 25-yard piledriver from David Prutton and moments later blocked a shot from substitute Junior Agogo.