Pakistan defied a stellar batting effort from Danushka Gunathilaka to win the final ODI by a comfortable margin of five wickets and ten balls to spare to take the three-match series 2-0.
Half-centuries from Fakhar Zaman, Abid Ali and Haris Sohail ensured Pakistan were never out of reach of the daunting target of 298 despite a few hiccups during the latter half of the chase.
Sri Lankan bowlers reignited hopes of a series-leveling with the dismissals of Babar Azam, centurion in the previous game, and Fakhar but they lacked the discipline to effectively capitalize on the breakthroughs and exert pressure on the opposition.
Pakistan eventually benefitted from a rollicking start to their innings by Abid, the 31-year-old making his comeback to the team after being unceremoniously dropped from the final World Cup squad.
Abid, who has repeatedly affirmed his admiration for batting great Sachin Tendulkar, showcased pristine timing as boundaries flew from his bat during the Powerplay.
Abid leaned on to his well-connected drives to perfection, dispatching the ball to the boundary fence ten times in his rapid contribution of 74 in just 67 deliveries.
His regal knock was reminiscent of the superb ton he struck on debut against Australia earlier this year, where Abid's wristy stroke play punished any ball off the radar.
Contrary to what is generally expected, Fakhar took the backseat and emerged as the reticent opening partner in the 123-run stand between the two.
The left-handed batsman took his time to get going and gradually acquired fluency while Abid attacked from the other end.
Fakhar, nevertheless, reached his second successive half-century, hitting seven fours and a six from an expansive hoick over cow corner off Wanindu Hasaranga.
He departed for a well-composed 76 off 91 deliveries when he tried to upper cut towards the boundary line only managing to guide it straight to third man.
Pakistan's innings then threatened to wilt away given captain Sarfaraz Ahmed's struggles in the middle but Haris calmly marshaled the chase to take his team over the line with a brief supporting act by Iftikhar Ahmed towards the end.
Iftikhar, twice in as many matches, added the exquisite finishing touch to Pakistan's innings through his aggressive shot-making.
Gunathilaka's batting masterclass
Days after the tourists' top-order crumbled against a fiery new-ball spell from Usman Shinwari, Sri Lanka were heralded by a supreme knock from Gunathilaka.
The 28-year-old asserted his dominance with a career-best score of 133, eclipsing his fellow teammates who failed to convert starts into substantial contributions.
He toyed with the Pakistan bowlers, effortlessly piercing the gaps with elegant drives to all corners of the park.
Hefty stands with skipper Lahiru Thirimanne, Angelo Perera and debutant Minod Bhanuka allowed Gunathilaka to progress smoothly amidst the sweltering Karachi heat.
His 134-ball stay at the crease was embellished with 16 fours and a solitary maximum that came off the bowling of Wahab Riaz.
Gunathilaka's wicket slightly halted Sri Lanka's momentum as Mohammad Amir pegged them back with quick wickets but Dasun Shanaka muscled a quickfire 43 from 24 balls to help his side post 297-9 in 50 overs.
Pakistan's chase began sedately but once Abid launched his crispy shots, the visitors could do little to thwart them.
While the first ODI was washed out due to persistent rain, the remaining two encounters provided plenty of entertainment to the Karachi crowd, who witnessed the return of 50-over cricket to their city since 2009.
The action now shifts to Lahore for the three-match T20I series scheduled to take place between October 5 and 9.