| This section needs additional citations for verification. (March 2024) |
Prior to serving on Parliament, Kariyawasam held leadership positions with National Youth Front, the youth wing of the United National Party. He served as the organization's chairman for the Kuliyapitiya Electoral District from 1995 to 1996 and chairman for the Kurunegala District from 1996 to 1999. In 1999, Kariyawasam was appointed general secretary for the organization's national operations.[3]
Kariyawasam served as a political organizer for the Panduwasnuwara Polling Division from 2003 to 2005, and for the Kuliyapitiya Polling Division beginning in 2005.[3]
Kariyawasam was elected to Parliament in 2004 representing Kurunegala as a UNP candidate. His party secured seven of 16 Parliament seats available in Kurunegala that year, with UNP candidates receiving 42.94% of all votes cast in the district.[6]
In the 2015 parliamentary election, Kariyawasam received the most votes out of any UNP candidate in the Kurunegala District, with 286,165 votes. He received the second-most votes among all candidates for the district across parties, only outplaced by former president and United People's Freedom Alliance candidate Mahinda Rajapaksa.[7]
In 2015, Kariyawasam was appointed minister of education while still serving on Parliament.[2] He held the position until 2019, and his tenure in Parliament ended in 2020.
Kariyawasam went on to serve as president of the Jathika Sevaka Sangamaya, a trade union affiliated with the UNP.[4]