Sineth Jayawardena is a left-handed batter who also bowls right-arm off-break. He came through Sri Lanka's youth pathway and featured prominently for the Under-19 side, eventually taking over the captaincy for the 2023 U19 Asia Cup in the UAE and leading Sri Lanka at the 2024 ICC U19 Cricket World Cup. He had already made his mark at youth level with a player-of-the-match 101 against Bangladesh U19 in a tri-series in the UAE.

Jayawardena made his senior debut for Panadura Sports Club in 2023, across First-Class, List A, and T20 formats, before moving to Tamil Union Cricket and Athletic Club. His List A career has included two centuries, with his highest score being a blistering 136 off 103 balls against Colombo Cricket Club, while he has also featured for Sri Lanka A, Sri Lanka Emerging, and Jaffna Kings in the Lanka Premier League.

In domestic T20 cricket, he has cemented his reputation as a destructive top-order option, highlighted by a rapid 101 off 52 balls against Panadura SC and a match-winning 82 off 32 balls in the final against SSC to lead Tamil Union to the 2026 title. Overall, he finished as the leading run-scorer in the Major Club T20 Tournament 2026, amassing 372 runs across 9 matches.

Having continued to develop through the domestic and Sri Lanka pathway setups, Jayawardena earned a place in Sri Lanka's 15-member squad for the 2026 Asian Games in Japan, where the side enters the men's T20 competition at the quarter-final stage.