[4] She also appeared in The Old Curiosity Shop, a 2007 ITV adaptation of the Charles Dickens novel of the same name starring Derek Jacobi, Toby Jones, Bradley Walsh, Zoë Wanamaker, Martin Freeman, Steve Pemberton, Anna Madeley and Gina McKee.

[5] In 2007, she appeared in the short Danger High Voltage at the Electric Picnic music festival in Stradbally, County Laois.

She appeared in the second episode of Single-Handed 2, broadcast on 1 January 2008, in which Garda Sergeant Jack Driscoll investigated the case of the missing two-year-old son of her character, Eilish.

[8] Whistleblower, a two-part fact-based drama broadcast in August 2008, was based on the late 1970s scandal at Our Lady of Lourdes Hospital in Drogheda, County Louth, involving gynaecologist Michael Neary.

[9] McKenna won the Outstanding Actress in a Mini-Series award for her role in Whistleblower at the Monte Carlo Television Festival in June 2009.

[12][13] Raw, a six-part series set in a fictitious restaurant in Dublin, saw McKenna interact with Bachelors Walk actor Keith McErlean and Mistresses actress Shelley Conn.[14] McKenna won the Best Actress (Television) award for her role in Raw at the Irish Film & Television Awards in February 2009.

In 2010, McKenna portrayed the young version of Josie, the love interest of vampire John Mitchell (Aidan Turner) in BBC supernatural comedy-drama Being Human.

[17] In February 2021, McKenna played a lead role as Detective Sergeant Niamh McGovern in the BBC police procedural drama series, Bloodlands.