Atif Qureshi hit 106 and Jack Williams 86 in a CBH total of 271-9 declared, but Widnes dramatically chased down to win with two overs to spare.
Missing Warren Goodwin and Lee Dixon, Chester gave a league debut to Reg Wyatt.
Winning the toss and batting first, Chester were soon in trouble on 10-2 losing Rick Moore and Alex Money to successive balls to Ben Hewitt. Luke Young (26) and Harry Killoran steadied things but Chester were still below par on 78-4.
Enter Atif Qureshi, fresh from 71 a week earlier. It's been a great first season for the unassuming allrounder and he and Jack Williams set about to turn things round.
Their fifth wicket partnership of 171 set up a declaration although the Chester tail didn't wag to add the additional 20-30 runs the skipper was looking for. For Widnes, skipper Tom Evans took 3-50.
Nevertheless, 271 felt comfortable but Chester failed to take early wickets and the hosts gradually got a foothold until Chris Kirby (24) eventually went with the score on 52.
Ali Chugtail (63) and Luke McCoy (42) then took advantage of some average bowling from the visitors before two almost comical run outs seemed to put Chester in the driving seat.
However, Majid Majeed had other ideas quietly masterminding victory with a compelling innings of 86*, aided at the end by Hewitt (22).
A boisterous home crowd celebrated what at one stage had seemed an unlikely victory while a shell shocked Chester reflected on what might have been.
Never week sees Chester at home to Didsbury.