Hibs skipper Liam Craig missed a first half penalty and the game looked to be heading for a dull goalless draw at Tynecastle until Nicholson and Buaben eased the pressure on Hearts. Buaben scored from the penalty spot after Scott Robertson pushed him in the area to concede a penalty and see red.
Hearts striker Osman Sow was also dismissed in the closing stages after he caught Michael Nelson in the face with an elbow and Alan Stubbs’ side rallied to pull a goal back through Farid El Alagui in time added on, although it proved too late to inspire a Hibs rally.
A lacklustre first half saw both sides compete hard without creating many clearcut chances, although Hibs were offered the perfect chance to break the deadlock.
Young Hearts goalkeeper Jack Hamilton was adjudged to have brought down Danny Handling as he came for the ball but Craig dragged his penalty wide of the post.
Hearts defender Jordan McGhee fizzed a shot just past the upright in first half stoppage-time as the teams went in in level at the break.
It took a moment of magic from Nicholson to break the deadlock as he nutmegged Robertson before drifting in a 25-yard shot via the post to give Robbie Neilson’s side the lead on 76 minutes.
Robertson was then dismissed three minutes later for a second bookable offence after he pushed Bauben in the area and the Ghanaian confidently side-footed his kick into the top corner.
Hibernian rallied and El Alagui’s header was saved at point-blank range by debutant Hamilton.
Former Crystal Palace player Sow was sent off two minutes from time for an elbow on Nelson over by the touchline to offer further hope to Hibs and they duly pulled a goal back in added time.
Frenchman El Alagui hooked in a delightful shot from the edge of the area but it came too late to prevent their derby rivals from claiming victory.