He made his first-class debut for Sebastianites Cricket and Athletic Club in 2005. He has also represented the Sri Lankan A squad. The closest he came to national recognition was when he was included in the 30-member provisional squad for the 2009 ICC World Twenty20 in England, but he was left out of the final 15 squad. That call-up came close on the heels of his maiden first-class ton, 135 for Basnahira South against Ruhuna Royals in the SLC Inter-Provincial Tournament, a match in which he also claimed five wickets. In 2012, Milinda went over to England to become Bury CC's professional for the 2012 season but his stay was cut short as he was selected to play in the Sri Lanka Premier League.

In March 2018, he was named in Dambulla's squad for the 2017–18 Super Four Provincial Tournament. The following month, he was named as the vice-captain of Dambulla's squad for the 2018 Super Provincial One Day Tournament.

On 11 July 2015, Milinda made his One Day International (ODI) debut at the Rangiri Dambulla International Stadium in the ODI series against Pakistan.

He scored his first ODI fifty in the fifth ODI in Pakistan series, where him with skipper Angelo Mathews had a unbeaten partnership of 114 runs. Sri Lanka posted their highest ever ODI total against Pakistan by scoring 368/4 in 50 overs.

He made his Twenty20 International debut for Sri Lanka against Pakistan on 30 July 2015. He was the highest run scorer for Sri Lanka in that match, where he had quick 35 runs, until he gets caught. Sri Lanka eventually lost the match at the end. His first T20 international wicket came on second match of the series, where he took the wicket of Shoaib Malik.

Milinda made his Test debut on 14 October 2015, against the West Indies. Before gaining the Test cap, he scored a unbeaten century in the three-day practice match against the same side.^[7]

In the second match of the series, Milinda top scored valuable 68 runs where Sri Lanka were all out for 200 runs in first innings. He showed a good talent with the ball, where he took 2 wickets for 25 runs and with the help of pacer Dhammika Prasad, who got 4 wickets, Windies were all out for 163. In the second innings, Milinda again scored quick 42 runs, just lost his maiden Test fifty. As Sri Lanka only scored 206 runs, Windies only required 244 runs to win the match and level the series. They were at good position to win the game with 1 for 81 runs, Milinda strikes and broke the partnership. West Indies could not come back and Sri Lanka finally won the match by 72 runs and won the series as well. Milinda took his best bowling figures by getting 3 for 25 runs and due to his allround performance, he adjudged man of the match as well.^[8]

After average performance in the Test series against England, Siriwardana was dropped from being named to 5-match ODI series.^[9] He was named back to the squad for the 3-T20I serie