Boyd, who has worked for Go-Ahead as a consultant at various agencies in recent years, joins only two months after the group was handed a £2m fine for two breaches of health and safety law that contributed to the Paddington rail crash in 1999.
Thames Trains, involved in the crash, has since been taken over by FirstGroup.
Go-Ahead group deputy chief executive Chris Moyes said the decision to hire Boyd meant all political communications would be handled in-house, with only occasional project work to be bought in.
'In the past, we have outsourced PA advisory work, and for quite a long time, Boyd was that adviser, first at Ludgate Public Affairs, then Politics International, and more recently at Consolidated,' said Moyes.
Boyd's role is to manage public affairs for the group's range of subsidiaries, which include Thameslink and South Central train services, as well as London and Brighton bus services.
Boyd was most recently head of corporate affairs at Britannic Group's retirement life company Britannic Retirement Solutions.