He has written for theatre, films and television, often writing about historical events or figures such as Queen Elizabeth II, whom he has covered extensively in all major media.

[citation needed] Morgan wrote television scripts during the 1990s, including an episode of Rik Mayall Presents... and the Comedy Premiere The Chest.

He also served as additional writer for Madame Sousatzka (1988), co-writer on the short film Dear Rosie (1990), and wrote re-writes for the comedy King Ralph (1991).

In 2006 The Queen was released, which showed how the death of Princess Diana impacted Prime Minister Tony Blair and the Royal Family.

In May 2007, the 50th San Francisco International Film Festival honoured Morgan with the year's Kanbar Award for Excellence in Screenwriting.

The film also starred Kevin Bacon, Rebecca Hall, Mathew Macfadyen, Toby Jones, Oliver Platt, and Sam Rockwell.

Roger Ebert gave the film 4 stars praising the writing and the performances of the leads saying, "Frank Langella and Michael Sheen do not attempt to mimic their characters, but to embody them".

The film received five Academy Award nominations including Best Adapted Screenplay for Morgan as well as for Best Picture losing to Slumdog Millionaire (2008).

Barry Morgan of The Associated Press declared, "With its well-chosen cast and high production values, “Relationship” is an especially thoughtful, revealing and honest account of power and politics.

[11] The Daily Telegraph's Mandrake diary reported in April 2010 that Morgan had quit the production after Sam Mendes was hired to direct, and that Patrick Marber would replace him.

[14] The film was directed by Ron Howard and written by Morgan and starred Chris Hemsworth, Daniel Brühl, and Olivia Wilde.

The play revolves around the weekly meetings, called audiences, between Queen Elizabeth II and her prime ministers over the time period of her reign.

Time Magazine film critic Stephanie Zacharek wrote, "In strict filmmaking terms, Bohemian Rhapsody is a bit of a mess.

Morgan is the creator and writer of the Netflix fictional historical drama series The Crown, a biographical story about the reign of Queen Elizabeth II.

The first season starred Claire Foy, Matt Smith, Vanessa Kirby, as Queen Elizabeth II, Prince Philip, and Princess Margaret, respectively.

Jared Harris and John Lithgow made supporting turns as King George VI and Winston Churchill.

The casts saw changes for seasons 3 and 4 with Olivia Colman, Tobias Menzies and Helena Bonham Carter replacing, Foy, Smith, and Kirby.

[17] The season marks the introduction of Emma Corrin as Diana, Princess of Wales, and Morgan's then girlfriend Gillian Anderson as British Prime Minister Margaret Thatcher, with Colman, Menzies, Bonham Carter and Josh O'Connor reprising their roles as Queen Elizabeth II, Prince Philip, Princess Margaret and Prince Charles respectively.

[20] Imelda Staunton, Jonathan Pryce and Lesley Manville played the respective roles of Queen Elizabeth II, Prince Philip and Princess Margaret.

[21] In May 2022 it was announced that Patriots, Morgan's first play since The Audience would preview at the Almeida Theatre in London from 2 July with an opening night on 12th and performances until 20 August.

Michael Stuhlbarg starred as Berezovsky and Will Keen and Luke Thallon reprised their roles as Putin and Abramovich respectively.

Morgan was appointed Commander of the Order of the British Empire (CBE) in the 2016 New Year Honours for services to drama.