Dempsey joins as Attack Coach and will head to the West Country ahead of the 2018/19 season.
The former Irish international played a key role in Leo Cullen's coaching team at his previous club Leinster. During his tenure the 42-year-old has worked alongside the likes of Stuart Lancaster, Joe Schmidt and Michael Cheika.
Prior to that Dempsey spent two seasons as Elite Player Development Officer for the province, and a further three years as Academy Manager learning his craft and developing playing talent in the province.
Dempsey brings a tremendous amount of experience to Bath, not only from his coaching career but also his playing career that saw him capped 82 times by Ireland, which included him playing in three Triple Crown winning teams. He has also enjoyed both Heineken Cup and Celtic League success as a player with Leinster.
Girvan’s appointment is part of Bath Rugby’s long-term plan for developing the right support structures to deliver successful and consistent performances in both domestic and European rugby.