The screen legends - who won awards at last year's ceremony - have been confirmed as three of the many celebrities to hand out the highly-regarded prizes at the 82nd Academy Awards on March 7.
Last year, Sean won the Best Actor Oscar for his performance in 'Milk', while Kate gave a teary acceptance speech after being awarded the Best Actress gong for 2008's 'The Reader'.
Penelope - who took home the Best Supporting Actress honour for 'Vicky Cristina Barcelona' in 2009 - is up for another accolade this year.
The 35-year-old Spanish beauty has been nominated for her supporting role in musical movie 'Nine' - which also stars Daniel Day-Lewis, Marion Cotillard, Dame Judi Dench, Fergie, Kate Hudson, Nicole Kidman and Sophia Loren.
Late star Heath Ledger was the other major acting award winner at last year's show. He was honoured with the Best Supporting Actor Oscar for his performance as The Joker in Batman blockbuster 'The Dark Night'.
He died tragically in January 2008 from an accidental drugs overdose aged just 28.