Ward had been struggling with a hamstring injury since limping off in the reverse fixture against Forest at the City Ground on September 30.
After a couple of substitute appearances and a run out for the reserves, the diminutive forward was named in Nigel Clough's XI for the east midlands derby and netted his sixth goal of the season early in the second half to earn Derby a 1-1 draw.
Cohen had put Forest in front just after the half hour mark.
Midfielder Craig Bryson returned to the Rams' side along with Ward following a four-match absence with a knee injury.
The two changes meant that Ben Davies and Kieron Freeman dropped down to the bench.
Forest boss Alex McLeish made just one change for his first derby clash as captain Danny Collins returned at centre-half after suspension in place of Dan Harding.
Derby, cheered on by the majority of a full house at Pride Park, started brightly.
Bryson narrowly missed the target with a 20-yard effort before Ward went close with a free-kick.
Forest weathered the early storm and settled into the game, with Simon Cox striking the crossbar with a shot from the edge of the area after 14 minutes and Gonzalo Jara Reyes going close shortly afterwards.
But the Rams were soon in the ascendancy again, piling on the pressure but without actually testing young goalkeeper Karl Darlow.
It was against the run of play when Forest went ahead in the 31st minute.
After good build-up play from Radoslaw Majewski and Billy Sharp, the ball fell to Cohen at the far post.
He needed two bites of the cherry, scuffing his first effort, but guided a shot past Adam Legzdins from 10 yards out.
Derby responded with John Brayford and then Ward sending shots wide before the break.
Ward brought the hosts level after 52 minutes. Simon Gillett turned into trouble in the middle of the park and was tackled by Conor Sammon, who slid a pass through to his strike partner to finish neatly underneath Darlow.
McLeish brought on Dexter Blackstock for Majewski just after the hour mark and went with three up front in an attempt to win the game and the tactical switch caused Derby problems as Forest finished strongly.
Cox and Cohen both went close with long-range efforts either side of the midway point of the second half and Sharp saw a couple of efforts go narrowly wide inside the final 10 minutes.
But the Rams, who had won the last three matches against their east midlands rivals, held on for a point and Forest will feel they missed an opportunity to move within touching distance of the teams in the play-off places ahead of the 3pm kick-offs.