A year later he played one of the leads in Children of the Wolf, with Sheelagh Cullen and Yvonne Mitchell at London's Apollo Theatre. Briant was subsequently nominated for the 'Best Newcomer' award by the London theatre critics that year for this role. Put under contract at Elstree Film Studios in late 1973, Briant starred in four films; Straight on Till Morning, Frankenstein and the Monster from Hell, Captain Kronos - Vampire Hunter and Demons of the Mind. He also appeared in television series such as Van der Valk, The Sweeney, and Jack Gold's The Naked Civil Servant with John Hurt. During this time Briant appeared in many BBC drama series and Plays of the Month, most notably Warris Hussein's Notorious Woman opposite Rosemary Harris, George Chakiris and Jeremy Irons. In 1973, in Hollywood, he played the title role in Glenn Jordan's The Picture of Dorian Gray a two part Movie of the Week for America's ABC network. Other later film and television credits include John Huston's The Mackintosh Man with Paul Newman; guest starring in Jeffrey Bloom's Veronica Clare; playing Jack Palance's son in the film Hawk the Slayer; starring in David Wolper's Murder is Easy with Olivia de Havilland; and Just Jaekin's Lady Chatterley's Lover.

Since the early 1980s, much of Briant's acting work has been in Australian and New Zealand films and television. He has starred in 14 films in Australia and New Zealand, including Simon Wincer's The Lighthorsemen, Shaker Run, Chamelian 3, Grievous Bodily Harm, Run Chrissie Run! and Cassandra. His TV credits include: Anzacs, The Flying Doctors, Bodysurfer, Darlings of the Gods, The Man from Snowy River, Wildside, Mission: Impossible, Murder Call, the European co-production Mission Top Secret, All Saints, False Witness and the American sci-fi series Farscape and Time Trax. Briant portrayed the governor of Bombay in Roland Joffé's epic drama Singularity.

The first short film he wrote, A Message from Fallujah won the "Best of the Fest" award at the 2005 Los Angeles International Short Film Festival and was in the final mix of ten shorts for consideration for an Academy Award that year.

Briant has had seven novels published in Australia and one in the United States. In Australia, The Webber Agenda (1994), The Chasen Catalyst (1995), Hitkids (1999), Bite of the Lotus (2001) and Graphic (2005) 'Worst Nightmares' and 'The Dreamhealer, and in the United States 'Worst Nightmares.' His American released novel, Worst Nightmares was published in hardback by Vanguard Press in 2009 to universally great reviews; a mass market edition was published in 2010. Shane finished the sequel on 3 March 2011, The Dreamhealer. His latest novel, Live Feed, a scathing indictment on the electronic media couched within the framework of an exciting thriller, was released on Amazon.com and Createspace.com in July 2015. He has written an autobiography titled 'Always the Bad Guy' which is only available online at Amazon.com