He made his feature film debut in 2007 with a supporting role in Sweeney Todd: The Demon Barber of Fleet Street.

In 2022, Bower featured as Henry Creel / Vecna in the fourth season of the Netflix fantasy series Stranger Things, for which he received critical acclaim.

[8][9] His maternal great-great-great-great-grandfather was Sir John Campbell, of Airds, Lieutenant Governor of Saint Vincent and the Grenadines.

In 2007, he co-starred as Anthony Hope in Tim Burton's Sweeney Todd: The Demon Barber of Fleet Street.

In June 2015, Bower began playing the role of Joe in the West End musical Bend It Like Beckham.

He played the role of the poet, gay atheist and spy Christopher Marlowe who was jealous of Shakespeare.

Since 2015, Bower has voiced Skiff in the Thomas & Friends franchise, having contributed to the television show, two home videos, and the feature film Sodor's Legend of the Lost Treasure.

[21][5][6] Originally, Bower was the lead singer of the band The Darling Buds, which never released an album and that dissolved in June 2015.

He stated: "As far back as I can remember, whenever I picked up a microphone, it was harder for me to sing wholly in a British accent than to just wail away and drop my T’s or bend notes so it almost sounds American".

In a 2019 interview he told that some artists who influenced his career are Placebo, Deftones, Blur, Oasis and Marilyn Manson.

[30] In a 2022 interview he said that his greatest inspiration during his solo career are The Cure, especially their album Pornography, and also black metal artists such as Sunn O))), Mayhem, Darkthrone and Carpathian Forest, especially when preparing for his role in Stranger Things as Vecna.

[45][46] In February 2010, Bower was confirmed to be dating actress Bonnie Wright, whom he had met on the set of Harry Potter and the Deathly Hallows – Part 1.

Remember, we are all works in progress J x”[51] Bower has several times opened up about his past struggles with alcoholism, drug abuse and mental health illnesses.

[53] Then, in July 2022, he shared on Twitter that in the past he was recovered in a mental health hospital for his addiction and he also talked about his sobriety, and many organizations involved in mental health, such as Turning Point and High Watch Recovery Center, praised Bower for his words;[54][55][56] and in September 2022 he said that he grew up with anxiety and that, when he got older, he needed alcohol to relieve fears and insecurities.