The actresses both star as royal sisters Queen Elizabeth II and Princess Margaret in the newest season of the critically-acclaimed Netflix series.
Fellow stars Jason Watkins, Tobias Menzies, Erin Doherty and Josh O'Connor also joined the duo at the screening at the Curzon cinema in Mayfair.
Oscar award-winning actress Colman, 45, wore a simple black gown with crew neckline and A-line skirt with a train, which she held on to with a ring.
She also carried a teal clutch bag and accessorised her dress with matching green and black earrings.
Meanwhile Bonham Carter matched her on-screen sister with a black prom-style dress with white and silver feathers and black high heeled shoes.
According to Netflix, the third series will see “a new guard sweep into Downing Street, as Queen Elizabeth and her family struggle to meet the challenges of a rapidly changing Britain,” attempting to adapt to “a new, more liberated, but also more turbulent world.
It covers 1964 to 1977, ending at the time of the Silver Jubilee, and will cover moments in history such as Harold Wilson’s time as Prime Minister, the Aberfan disaster and the Apollo 11 moon landing.
Bonham Carter has replaced Vanessa Kirby as Princess Margaret, while The Durrells star Josh O’Connor joins the cast as a young Prince Charles.
Menzies plays Prince Philip, Doherty stars as Princess Anne, Watkins as Harold Wilson, Ben Daniels as Lord Snowdon and Charles Dance as Lord Mountbatten.
Colman’s role comes after a standout year which has seen her awarded an Oscar, a Bafta and a Golden Globe for her portrayal of Queen Anne in Yorgos Lanthimos’ film, the Favourite.
Ahead of its release, the new series of The Crown has received generally positive reviews from critics.
The Crown returns to Netflix on Sunday, November 17.