He is a old Thomian of Saint Thomas" College, Matale. After playing for the school matches, he has picked to the under-19 cricket team for the Quadrangular Under-19 Series in 2011. He showed immense talent within the series, where his knock of 63 and 4 for 17 runs against India U-19, produced only in the losing side with just 5 runs short.
Within the series, against Australia U-19s, Lahiru scored an unbeaten 56 runs, giving the team total of 225.
Australia finally ost the match by 86 runs. On 2012, Lahiru was picked to the Under-19 World Cup 2012.
The first match for Sri Lanka was against Namibia U-19s, where Lahiru was able to pick up 4 for 15 runs. On 2015 cricket season, Lahiru played for the Bloomfield in Salt Lake City Twenty20 Tournament 2015.
He scored his highest T20 score of 41* runs against Sri Lanka Air Force Sports Club.
Madushanka was included to the Sri Lanka A team for the tour in New Zealand and played the second unofficial ODI. However, he didn"t include for the rest of the matches and Sri Lanka A finally lost the series to 3-2.