Ravi Bishnoi took two wickets for 31 runs for LSG.
Chasing the target, LSG were restricted to 154 for 8.
Deepak Hooda top-scored for LSG with 59 off 39 balls while Marcus Stoinis contributed 27.
Boult, Obed McCoy and Prasidh Krishna grabbed two wickets apiece while Yuzvendra Chahal and Ravichandran Ashwin got one each for the Royals.
Brief Scores:
Rajasthan Royals: 178 for 6 in 20 overs (Yashasvi Jaiswal 41, Devdutt Padikkal 39; Ravi Bishnoi 2/31).
Lucknow Super Giants: 154 for 8 in 20 overs (Deepak Hooda 59; Trent Boult 2/18, Obed McCoy 2/35, Prasidh Krishna 2/32).