One Direction and Emeli Sandé have also been named as performers at the event, which will be held at London's O2 Arena on February 20.
Mumford and Sons and Ben Howard complete the initial lineup, while further live acts may be confirmed at a later date.
> Brit Awards 2013: Nominations in full
Williams was previously rumoured to be headlining the awards ceremony, as organisers were convinced that he would take home the 'Best British Male' trophy.
However, he has not been nominated for the category this year, but has been recognised for 'Best British Single' for his chart-topper 'Candy'.
Emeli Sandé leads the pack this year with four nominations, while Mumford and Sons, Alt-J and Rita Ora have been nominated for three each.
The nominations were announced in London earlier tonight (January 10).
Watch Robbie Williams perform a medley of hits at the Brit Awards 2010 below:
Brit Awards 2013 nominees in pictures: