Matthew Spriegel's all-round excellence propelled Surrey to the top of the Clydesdale Bank 40 Group B table and dented Nottinghamshire's own hopes of reaching the knock-out semi-finals.
A used pitch gave both sets of bowlers plenty of assistance, especially the spinners, but Spriegel's innings of 47 was key after he had earlier opened the bowling and taken 2-21.
Nottinghamshire's 149 all out had looked substantially short of being competitive as Jade Dernbach (3-39) and Gareth Batty (2-26) also enjoyed success.
Early wickets for Harry Gurney (2-23), together with a tight spell from Steven Mullaney (2-24) dragged the home side back into the contest, until Spriegel hit three fours and two big sixes in a 61-ball stay to help guide Surrey home with four wickets and 23 balls to spare.
It meant a happy return for Rory Hamilton-Brown, playing his first game since taking a break from action following the tragic death of team-mate and close friend Tom Maynard.
Visiting skipper Batty's decision to bowl first was soon proven a wise one as Notts were reduced to 52-4 by the 10th over.
Michael Lumb was bowled trying to cut Spriegel, who also had Riki Wessels caught at short midwicket.
In between, Samit Patel top-edged Dernbach to long leg before the paceman returned to oust Alex Hales (25) as the opener drove loosely to Zander de Bruyn at point.
It was left to Adam Voges (36) and Chris Read (35) to rebuild the innings and they shared a stand of 67, but it took 18 overs to put together and produced just one boundary.
Voges' demise - caught at slip by Gary Wilson off Murali Kartik's turning lifter - was the first of the final six wickets to fall for 30 runs in eight overs.
Surrey were immediately in trouble at 3-2 in their reply as Gurney claimed the wickets in successive balls of Hamilton-Brown and Jason Roy, the latter with a brute of a lifter.
Steven Davies (35 from 42 balls) and Wilson (29) calmed the visitors' nerves with a partnership of 60 from 14 overs, before the former skied Mullaney's fourth ball to Voges.
Wilson followed, being stumped by Read off Graeme White, and De Bruyn also fell cheaply, but Spriegel kept Surrey ahead of the required run-rate.
The left-hander fell just short of fifty as he tried to smash White for a second successive maximum and was caught on the ropes by Wessels.
But he had already done enough, leaving Zafar Ansari (14no) and Batty (10no) to complete the formalities.