The US Open champion landed 11 aces and frustrated Paolini with powerful returns near the sidelines, with the Italian growing tired as the match progressed.
World number one Sabalenka has now won 60 matches on the tour this year.
"Doesn't matter the score, I always know I have to stay focused. If you give (Paolini) an opportunity she will take control of the game," Sabalenka said. "I was focused, I was calm and it feels like everything was in control."
Four-time Grand Slam champion Sabalenka got her first break with a backhand across the court to go 2-0 up.
Paolini troubled the world number one with low shots down the middle as Sabalenka's awkward forehand returns hit the net twice, with the Italian getting a crucial break to reduce the Belarusian's lead to 4-3.
But Sabalenka, who was the runner-up in the 2022 edition of the WTA Finals, broke again to go 5-3 up, before landing four aces in the next game to hold her serve and secure the set 6-3.
Sabalenka won the next four games to build up a 4-0 lead in the second set, which proved to be unassailable for two-time Grand Slam finalist Paolini.
Defending champion Coco Gauff was facing fellow American Jessica Pegula in the second match of their group later in the evening in Riyadh.
All four women in the group will play each other in a round-robin format, and the top two will qualify for the semi-finals.