Actor Harrelson, whose famous roles include barman Woody Boyd in sitcom Cheers and movies such as Kingpin and Zombieland, has been added to the Rest Of The World squad.
Australian Baker, 40, will also line up in the charity football match, which takes place on June 6 at Old Trafford. Organised by Robbie Williams, it will be broadcast live on ITV1.
Yesterday, Mike Myers, rugby player Danny Cipriani and comedian Paddy McGuinness signed up for the event.
Former Liverpool star Kenny Dalglish and Ian Rush will manage the Rest Of The World squad, which also includes footballers Zinedine Zidane, Henrik Larsson and Jens Lehmann, cricketer Brian Lara, Westlife's Shane Filan and Nicky Byrne, comic Patrick Kielty and Gordon Ramsay. Michael Sheen will captain the side, while Gethin Jones, Boyzone's Ronan Keating, Joe Calzaghe and Heroes star James Kyson Lee are also in the squad.
Robbie Williams will be joined in the England squad by GMTV's Ben Shephard, TV presenters Bradley Walsh and Jamie Theakston, actor Damian Lewis, boxing star Ricky Hatton and ex-footballers Alan Shearer, David Seaman, Teddy Sheringham and Jamie Redknapp.
Tickets for the match are on sale now.