Brar is set to step in following the brief tenure of Stephen Lotinga, who also joined from Bell Pottinger but was poached within weeks by deputy Prime Minister Nick Clegg, as the agency "refocuses" its public affairs offer.
Brar is a partner at Bell Pottinger and was previously executive assistant to Lord Turner, executive chairman of the Financial Conduct Authority, as well as a political adviser to Adrian Bailey MP.
Alex Bigg called Brar, who is also COO of networking group Labour in the City, a "breath of fresh air".
"He is young, ambitious and has an understanding of the power of social and what public affairs has to do to get a seat at the table. He has gained a lot of experience in a short space of time and is a class act."
Brar is due to join later this summer with the agency seeking to rebuild a public affairs team previously thought to number in the low twenties after a number of departures.
As well as the exit of Lotinga, who had replaced Chris Rumfitt, it is set to lose Dominic Pendry and energy specialist Jessica Lennard, with at least two more junior figures also believed to be leaving.
Of the changes, Bigg said: "We are refocusing the PA team away from a sector-specific approach to one where it is integrated into the wider Edelman offer. A PA team that focuses on working for bigger brands, issues and campaigns."
Bell Pottinger is losing Brar as it continues its efforts to replace Lotinga.
James Henderson, Bell Pottinger CEO, declined to comment on the move but said of Brar's departure: "Gurpreet is an exceptional consultant and we completely understand his decision to leave to become managing director of Edelman and wish him very well for the future."