Raiders have now set club history with their highest-ever finish in the National League, something which a string of impressive performances and results this season has deserved.
The bonus point win, combined with seventh-placed Canterbury's 35-14 defeat at home to Richmond, means Worthing are 12 points clear and uncatchable as both sides now have just two remaining games.
Head coach Will Green expressed his joy at sealing the sixth spot but also hinted at looking to go one better into fifth.
He said: "It's fantastic and is a reward for all the hard work we've put in over the season, so I'm delighted.
"It was something we set out to do at Christmas and we've achieved it now. We are very much looking to win the last two games and see where we end up now.
"I was very pleased with the performance on Saturday. We started well but did go off the boil a bit in the first half. But in the second we improved and put in a good display.
"We worked a bit harder, made gaps, opened them up and exploited them."
Raiders now travel to fifth-placed Southend on Saturday, a five-point bonus win there, will mean Worthing go into their final game of the season at Clifton still with a chance of claiming fifth spot.
Worthing started strongly and Joe Launchbury exploited Shelford's defence to score both of Worthing's early tries. He went over in the second minute, which Matt McLean converted, before touching down again just three minutes later, to put Raiders 12-0 ahead after just five minutes.
Shelford's Ed Gough put over a penalty after Worthing infringed. They then put a converted try down on 20 minutes after a burst down the left flank was shifted to Phil Bullen-Brown, who found a gap to go through. Gough added the extras.
Shelford again went over just three minutes later after a number of strong drives. Dane Grey made the final push to score on the right and Gough kicked the conversion and soon added a penalty as well.
Worthing got themselves back into it just before half-time, when Greg Sullivan scored their third try and McLean added the extras to make the half-time score 20-19.
After the break, it was once-way traffic as Worthing ran in five tries with no response from Shelford.
McLean got things underway as he took advantage of an overlap after a series of drives just a minute into the half, and touched down and put over the conversion himself.
Paul Dunckley was then on the receiving end of a try-scoring pass from Ben Dudley after some smart work and movement. McLean kicked his final conversion of the day to follow it up.
Raiders continued to dominate as Joe Govett put down two tries either side of his own penalty kick and substitute Will Smith's 73rd-minute try.
WORTHING: McLean, Govett, Sullivan, Dunckley, Walker, Dudley, Marsh, Emmett, Cleveland, Bennett, Launchbury, McGowan, Maidment, Redmayne, Taulava. Subs: Ryle, Costigan, Pointing, Bruce, Smith.
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