Faraz Shauketaly, a reporter with the privately-run Sunday Leader whose editor was shot dead in 2009, was rushed to hospital for surgery following the midnight attack at his home, according to his colleagues.
"Investigations are underway," police said in a statement but did not elaborate on the unidentified gunmen or the motive for the shooting.
Some 17 journalists and media employees have been killed in Sri Lanka in the past decade, with none of the murders being solved, according to rights groups.
In January 2009, editor of the anti-establishment Sunday Leader, Lasantha Wickramatunga, was shot dead near his office. He was a staunch critic of the government led by President Mahinda Rajapakse.
Attacks against journalists and news outlets have continued despite the end of the decades-long war between the military and Tamil Tiger separatist rebels that same year.
Sri Lanka lifted a state of emergency in August 2011, but media rights groups say journalists have been forced to self-c