Richard Flood portrayed the role of Samuel Johanson in an episode of the series Titanic: Blood and Steel in 2012.

He joined the main cast of the television series Crossing Lines in 2013, playing detective Tommy McConnel, a specialist in weapons and tactics from Northern Ireland, until 2014. That next year, in 2015, Flood joined the main cast of the series Red Rock, where he played the police superintendent James McKay.

In 2017, it was announced that Flood would be cast as Ford in the Showtime series Shameless. He became a series regular ahead of the ninth season. In 2019, Flood was cast in a recurring role as Dr. Cormac Hayes on ABC's Grey's Anatomy. He was promoted to star for the 2020–21 season.

Flood appears alongside Acushla-Tara Kupe in TVNZ+'s crime drama, The Gone, released in May 2023.

He left Clongowes in 2001 .