She was a founder-member of the Abbey Theatre and was leading lady on its opening night in 1904, when she played the title role in W. B. Yeats's Cathleen Ni Houlihan.

Nic Shiubhlaigh was born Mary Elizabeth Walker in Charlemont Street, Dublin into a nationalist and Irish-speaking family.

In 1901 the drama group took part in a feis with two plays, Tobar Draoidheachta by Father Dinneen and Red Hugh by Alice Milligan.

[citation needed] In 1902 Nic Shiubhlaigh joined W. G. Fay's Irish National Dramatic Company, along with others such as Maire Quinn, Brian Callender, Charles Caulfield, James H. Cousins, P. J. Kelly, Dudley Digges and Fred Ryan.

Their first production, of the two one-act plays, Cathleen Ni Houlihan, with Maud Gonne in the lead role, and Deirdre, was on 2 April 1902.

The company, which had no funds to speak of, acquired a couple of bare rooms at 34 Lower Camden Street, which with the help of friends from Irish-revival societies they turned into a tiny theatre.

She was the principal actress of the company after Máire Quinn's departure to America, and when she left, the burden of the chief women's rôles fell upon Sara Allgood.

[citation needed] In September 1905, the Abbey administrator and financial backer, an English theatre impresario called Annie Horniman, in hopes of improving the artistic quality of the productions at the Abbey, offered to guarantee salaries (a sum of £500 per year) for the actors and for Willie Fay as producer.

[citation needed] Nic Shiubhlaigh remained with the Abbey until December 1905, when along with Honor Lavelle (Helen Laird), Emma Vernon, Máire Garvey, Frank Walker, Seamus O'Sullivan, Pádraic Colum and George Roberts she left.

In 1929 she married former IRA Director of Organisation, Major General Eamon 'Bob' Price, and they moved to Laytown, County Meath.