Noteworthy illustrators, writers, and editors of the time, including William O'Brien, Ireland’s first investigative journalist, contributed to the paper.

[13] He established a career as a publisher and owner of newspapers, including influential nationalist titles such as the Flag of Ireland and the Irishman.

O'Brien significantly impacted Ireland's late 19th-century media practices with his pioneering investigative journalism at the time.

[1][13][17] The most popular serial on the paper featured the tales the fictitious character Mick McQuaid, created by Lynam in 1867.

[14] Lynam passed away in 1894, but The Shamrock and Mick McQuaid's stories continued with other writers, even after the merger with the Irish Emerald.