Lancashire, off the back of five straight victories, had been challenged to score 156 from 15 overs but could only reach 139 for eight, giving the defending champions the points by a margin of 16 runs under the DLS-method.
Earlier, Notts posted a score of 196 for nine, despite losing four wickets inside the opening six overs. Jake Libby and Billy Root, both inexperienced in this form of the game, re-built the innings with a well-constructed stand of 78 in 9.2 overs, in which both registered their highest scores in the format.
Libby scored 44 from 28 balls and Root, who played in last year’s final, stroked his way to 40 from 35.
Their departures heralded some late drama as Lancashire snatched three wickets in four deliveries but Dan Christian’s brutal 36 not out took the home side to the brink of 200.
Riki Wessels had played a stunning cameo at the start of the match, clubbing Graham Onions for four sixes in an over, before falling for 33 from only 13 deliveries faced.
Toby Lester, with three for 33, returned the pick of the bowling figures for the visitors.
Under threatening skies Alex Davies and Karl Brown plundered 29 runs from three overs – with Davies hitting four boundaries in Samit Patel’s opening over – before the heavens opened and the umpires sent the players scurrying back to the pavilion.
The restart couldn’t have been more dramatic, with Notts taking two wickets in as many balls. Davies was bowled by Patel for 19, then Arron Lilley was run out after sharp work from Will Fraine.
Keaton Jennings, given dispensation by the ECB to play after being named in England’s Test squad, didn’t hang around for long before being bowled by Patel, who ended with two for 26.
Karl Brown top-scored for Lightning with 49 from only 30 balls, which included four fours and two maximums but he then drilled Ish Sodhi to cover.
The contest was very much in the balance as Jordan Clark and Steven Croft perished quickly but James Faulkner revived hopes for the Red Rose by clubbing his first delivery for an enormous six but his promising innings was cut short as the Outlaws held firm for their first home win of the campaign, in front of a crowd of 11,267.
Notts are quickly back in action, facing Durham Jets in the north east on Saturday, whilst Lancashire Lightning are at Worcester on Sunday.