He is best known for his roles as Barry "Newt" Newton in the soap opera Hollyoaks (2007–2010), Finn Nelson in My Mad Fat Diary (2013–2015), Joe Middleton in The Village (2013), and Johnjo O'Shea in Common (2014).

[12] In 2010, Mirallegro appeared in an episode of the BBC drama series Moving On as a gay youngster who suffers bullying in school because of his sexuality.

He portrayed a young footman called Johnny Proude, who took up a position in service to escape the poverty of the northern mining town where he was born.

[11] In 2011, Mirallegro appeared in the BBC's three-part psychological thriller Exile,[16] playing the teenage version of leading character Tom Ronstadt.

[17] In 2013, he began playing Finn Nelson, the love interest of the main female character in E4's teen comedy-drama series My Mad Fat Diary.

[19] In 2014, Mirallegro portrayed a teenager prosecuted for murder under the Joint Enterprise law in the controversial BBC One production Common, written by Jimmy McGovern.

[20] Called "a bleak, powerful drama thick with political intent", a review started that Mirallegro "continues to prove himself as the best actor ever to graduate from Hollyoaks".

Mirallegro portrayed Kenan,[a] Noah's youngest (and extrabiblical) son, whose wish to follow a path different from his father and brothers results in his being swept away in the Great Flood.

In November 2023, it was announced by Paramount+ that Mirallegro would star in a new original drama series Stags, filming on location in Tenerife and due to be released in 2024.

The game is a baptism of fire for [Mirallegro's] character, David Campbell, who makes his Northern Ireland debut in front of 50,000 people the day before his 21st birthday".

[b] In January 2014, Mirallegro appeared at London's Royal Court Theatre in the drama The Pass,[31] in which Russell Tovey plays a football player coming to terms with his homosexuality.