Dowler is one of FD's longest serving members of its senior team, having first joined the agency in 1993.
His start date at Finsbury is not yet known. It is understood FD communicated the move internally this morning.
Dowler has specialised in M&A, restructuring projects and private equity deals and has worked on high profile transactions, such as Terra Firma's acquisitions of EMI and ABN Amro's sale to Royal Bank of Scotland.
He also advised British Energy around its £5bn restructuring on all aspects of the company's communications including relations with shareholders, bondholders, analysts, the media and the UK Government and subsequently on the company's £12.5bn sale to EDF.
He also previously served as managing director of FD's consumer sector.