His other film and television appearances include Cal (1984), The Secret Garden (1993), In the Name of the Father (1993), Sliding Doors (1998), The Fall (2013–2016), Medici (2019), The Head (2020–2022), The Banishing (2021), and Blue Lights (2023.

He began acting in Irish language plays at school during the early years of The Troubles in Northern Ireland.

These include Cal (1984) with Helen Mirren,[5] for which he was nominated for the BAFTA Award for Most Promising Newcomer to Leading Film Roles,[6] The Railway Station Man (1992) with Julie Christie and Donald Sutherland, In the Name of the Father (1993) with Daniel Day-Lewis, Nothing Personal (1995) and Some Mother's Son (1996), also with Mirren, as well as the Irish-themed film Evelyn (2002).

[7] In Some Mother's Son, he played the role of Irish Republican hunger strike leader Bobby Sands.

He played the role of Wollfstan in Black Death, and appeared in the 2012 film version of Michael Morpurgo's novel, Private Peaceful.

[5] Lynch married film-maker Mary McGuckian in 1997, having met her on the set of Words Upon the Window Pane a few years earlier.