Bowler, who was IRS chairman from 2001 to 2003 and a board member for five years, launched the operation last week. The offering will run alongside Haggie's corporate and financial services business.
Bowler has been working as a freelance consultant for the past six months after leaving College Hill Associates in 2004.
He was briefly head of the firm's IR practice and worked for clients such as Old Mutual and Philips.
Before College Hill, Bowler spent five years as head of IR at insurance group Guardian Royal Exchange. He also spent four years as corporate affairs manager at automotive services group Inchcape and was PR manager at Granada TV Rental.
Bowler said Haggie's IR division would call on staff from the 12-strong firm and provide strategic IR advice. He added that he would target the private client investment market.
Diane Faulks replaced Bowler as IRS chair in 2003 and is due to step down later this year.
Bowler reports to the firm's founder David Haggie.