Former Scottish international, McGeechan, toured with the Lions in 1989 and 1993 before coaching the side in 1997, 2005 and most recently during the 2009 tour of South Africa.
Geech joined Bath as performance director at the beginning of the season and has gradually assumed more responsibility at the the Rec. He was recently upgraded to director of rugby.
Meehan will not be replaced with the remainder of the coaching staff taking full responsibility next season.
During his time with Bath Meehan has lead them to three Premiership semi-finals and a European Challenge Cup triumph in 2008. He has been linked with a move back to Stade Francais where he coached prior to joining Bath but has called on his side to concentrate on the remainder of the season.
"Over the past five years we've developed our style of play, played some terrific rugby, won the respect of all the clubs in the Premiership and challenged some of the biggest teams in Europe," said Meehan.
"It's been a challenging yet enjoyable period, but the timing is right for me to move on at the end of this season and I wish the team every success in years to come.
"However, the key part of this season is now upon us and before I leave I will be doing everything I can to ensure we are in the play-offs and going for the title."