The revamp sees Brazen take responsibility for Hasbro's Knex, Transformers, Monsters Inc, Micro Machines and Creative Play.
The agency is also responsible for consumer launches of TV tie-in The Simpsons Cluedo, adult board-game Saint or Sinner, and My Monopoly, a customised version of board-game Monopoly.
The account work started this week with Brazen handling the launch of the Star Wars Episode II toy range.
The agency is undertaking both reactive work and proactively attempting to place news stories on behalf of the company's brands.
The agency will report to Hasbro marketing director Carol Evans. Brazen joins Mason Williams , which works on Hasbro's pre-school brands, and Lexis PR, which handles PR for the BeyBlades and Action Man lines, on the Hasbro roster.
The appointment of Brazen is understood to be the final part of Hasbro's PR overhaul, which saw the bulk of the marketing team - that had been seeing pitches from an initial long-list of consumer agencies - made redundant during the process (PRWeek, 8 February).
As part of Brazen's assumption of press office duties, agency staff are working in-house at Hasbro's corporate headquarters for two days a month in order to ensure close collaboration with Hasbro's marketing function.
Agency founder Neena Wheeler, who was a director at Mason Williams before setting up Brazen last year, said: 'We are the people to contact for media enquiries and we can act as an in-house team.'