McGuinness has been ruled out of the TT after sustaining injuries in a practice crash at the North West 200.
Aussie Brookes will compete in both Monster Energy Supersport races on the Jackson CBR600RR Honda. The British Superbike rider will also compete for Norton alongside fellow countryman David Johnson in the RST Superbike and PokerStars Senior races.
Brookes is due to make his debut this year in the Lightweight race at the TT, when he will ride for Ryan Farquhar’s KMR Kawasaki team.
Farquhar is also running Lee Johnston, Peter Hickman and Danny Webb on his Kawasaki ER6 machines at the festival.