Webb played an influential part in the Lions' Southern Premier League Division One title success in 2018, hitting unbeaten centuries against Calmore Sports and Old Tauntonians & Romsey soon after joining the Chapel Gate set from High Wycombe.
But after scoring an undefeated 141 at Basingstoke in Bournemouth's opening match last season, his form tailed off with only one subsequent fifty in an eventual 340-run aggregate.
Webb has confirmed that his Chesham return is simply to do with logistics.
"I am based in London permanently now due to my career and therefore playing club cricket closer (to London) makes sense for me. With my history at Chesham, that was the obvious choice, it's a great club," he explained.
Webb will, however, continue to skipper Dorset, newly promoted to the top tier of the rebranded National Counties Association this summer.
Webb's Chapel Gate exit comes hard on the heels of left-arm spinner Dom Clutterbuck's decision to join Premier Division champions Bashley (Rydal).
But Bournemouth have snapped up South African pace bowler Adam Mather, who joins from Surrey Championship club Valley End.