They attended AFI Fest, where the newest series of the royal biopic was shown for the first time in the US a day before it airs on Netflix.
The American Film Institute had chosen to honour the Emmy-nominated programme with a high-profile presentation evening dubbed "an evening with Peter Morgan".
A conversation with writer and producer Morgan and a tribute to his career as an award-wining historical drama creator were features of the night.
Anderson, who will play Margaret Thatcher in the much anticipated season four of the acclaimed Netflix programme, stunned in a white, velvet Grecian-style dress paired with red stilettos.
The Sex Education actress was given the royal seal of approval by Colman this week, who called Anderson's portrayal of the Iron Lady "brilliant".
Colman wore a tailored white boat neck dress with black beaded wrap skirt wrapped around the waist to this glam event.
Bonham Carter, who plays Princess Margaret, sported a long, black dress with textured and floral panels and a small red bag.
Erin Doherty, who has taken up the role of the Queen's only daughter Princess Anne, stunned in a floor length black and white dress adding yellow shoes for a pop of colour.
The men also dazzled, with Morgan wearing a plush navy suit while Lithgow went for tailored black suit, navy shirt and green tie.
Josh O'Connor, who will now play an adolescent Prince Charles, wore a khaki suit and oversized, untucked blue and white striped shirt.
Viewers can catch the whole season as it drops on Netlix at 8am Sunday, November 17.