Oshane Thomas took five wickets for 28 runs with his rapacious fast bowling as West Indies inflicted Sri Lanka's sixth straight defeat in Twenty20 internationals on Wednesday.
Lendl Simmons hit an unbeaten 67 as West Indies, who chose to bat, made 196 for four to set up the 25-run win in the opening match of the two-game series.
Still hurting after losing the one-day series 3-0, West Indies smashed nine sixes in their innings as they dominated the Sri Lankan bowlers.
Simmons and Brandon King, who hit 33, put on 74 for the first wicket to lay the foundation for the challenging total.
Andre Russell then made 35 off 14 balls and captain Keiron Pollard, in his 500th T20 match, hit 34 off 15 to give a spectacular finish to the innings.
Thomas's bouncer-laden fast bowling devastated the Sri Lankan batting and they were all out for 171 in the final over. Kusal Perera top-scored with 66.
Opener Avishka Fernando, Shehan Jayasuriya, Kusal Mendis and Angelo Mathews were all out caught while flashing at Thomas's fiery short-pitched bowling. Sri Lanka fought back from 56 for five but were never seriously in the hunt.
Pollard hailed Thomas's "brilliant" performance that he said was a "just reward" for his hard work to get back into the West Indies squad for this tour.
The second and final match of the series is in Pallekele on Friday.
SRI LANKA: Avishka Fernando, Kusal Perera (wk), Kusal Mendis, Shehan Jayasuriya, Angelo Mathews, Dasun Shanaka, Thisara Perera, Wanindu Hasaranga, Isuru Udana, Lasith Malinga (capt), Lakshan Sandakan
WEST INDIES: Lendl Simmons, Brandon King, Shimron Hetmyer, Nicholas Pooran (wk), Kieron Pollard (capt), Rovman Powell, Andre Russell, Fabian Allen, Dwayne Bravo, Oshane Thomas, Sheldon Cottrell