The Kings finished on 161-7, with Johnson Charles batting throughout the innings and scoring a superb 87 off just 59 balls.
Despite losing early wickets, Guyana Amazon Warriors navigated their chase through Shimron Hetmyer and Heinrich Klaasen, who built a 66-run partnership.
Klaasen would go on to score a sublime 61* from 46 balls to take Amazon Warriors to their first win of the season with 10 balls to spare.
Kings got off to a dream start, Charles combining with Faf du Plessis to reach 77-0 after six overs, the highest Powerplay score of the season so far. Yet Shamsi and Tahir highlighted their quality by restricting runs and picking up wickets that held up scoring for the Kings.
Tim David launched a late counter-attack, but it was Keemo Paul who shone with the ball in the final over, picking up two wickets and giving away just four runs, which saw the Kings end on 161-7 after 20 overs.
Guyana Amazon Warriors started their chase with intent, Chandrapaul Hemraj scoring five boundaries before being dismissed in the fourth over, with fellow opener Shai Hope then being caught out two balls later.
Nevertheless, Hetmyer and Klaasen worked together to score runs and keep the Warriors close to their target. Despite Hetmyer (32 off 21) losing his wicket, Klaasen would bat through to the end, and supported by Keemo Paul (21* off 10), managed to get his side across the line.
The win means Amazon Warriors have registered their first victory of the season, while St. Lucia Kings have suffered their second successive loss. (CPL)