Vaas joined Colts Cricket Club after leaving school and made his first-class debut against Galle Cricket Club in December 1990 aged 16. He joined Middlesex County Cricket Club for the 2007 cricket season as an Overseas registration. In 2008, he signed with the Indian Premier League (IPL) side Deccan Chargers on a contract worth $200,000. He played 4 matches for the Deccan Chargers team and picked 4 wickets at an average of 26.61 with an economy rate of 1.4. In 2009 he played some matches in P.Sen trophy for Mohun Bagan. He also joined Northamptonshire County Cricket Club for the 2010 T20 competition and found himself in the unusual position of opening the batting although he did well recording three half centuries. He subsequently signed a contract to join Northants for the entire 2011 and 2012 seasons. At the end of 2011 he was named their 'Player of the season' following a great all-round performance, having topped the bowling averages by taking 70 first-class wickets at an average of 21.44 apiece and also scoring 403 runs at an average of 26.9. Vaas was released by Northants at the end of the 2012 season due to persistent injury problems throughout the year.

Early years

Nearly 4 years after his first-class debut, after just 13 matches, Vaas made his Test debut for the Sri Lankan cricket team against Pakistan at Kandy in August 1994. Within his first year in the national side, he made a great impact guiding Sri Lanka to their maiden Test Match away victory against New Zealand at Napier, taking 5–47 & 5–43 and scoring 33 & 36 and being nominated Man of the Match. In the second test at Dunedin, only his sixth Test, he took his third five-wicket haul and was again named Man of the Match.

He was a regular member of the ODI side during the 1996 World Cup, playing in all six matches including the Final, where Sri Lanka defeated Australia to become world champions for the very first time.