Sam Collins had given the Rocks the lead seven minutes before half-time following a poor opening half in which Canvey rarely threatened.
But Chatting's introduction midway through the second-half gave the Gulls extra impetus and his low cross forced Rocks centre back Simon Peddie to turn the ball into his own net for an equaliser.
After that the hosts looked the only side who would win it, and so it proved as Bradley Woods-Garness hooked home a sensational winner in the 71st minute.
In an instantly forgettable first half, the only action of note was the goal. And that came seven minutes before the break as Kye Ruel was afforded space on the right to swing in a low cross and, with the Canvey backline appealing in vain for an offside, Collins slid the ball home from close range.
The closest Canvey had come until then was Ashley Miller's looping header over the bar from a deep James Hawes cross midway through the half.
And the Gulls were lucky not to go two down a minute before the interval when keeper Ashlee Jones - who'd looked unconvincing on corners - comically sliced Rickie Hayles' back-pass towards his own goal but recovered by racing back and hacking it clear.
And in first-half injury time Canvey almost equalised when Rocks failed to deal with Miller's long throw and Hawes stabbed wide in a crowded six-yard box.
Rocks' new striker L'Heureux Meuga had the ball in the net early in the second half from Tom Stephen's corner, but it was ruled out for a foul.
Then Bradley Woods-Garness had a great chance for the Gulls as he raced in on goal from a ball over the top, but his side footed effort was pushed away by the advancing Elliot Justham.
Harrison Chatting came on for Hawes on 64 minutes and had an immediate impact. The former Billericay winger received the ball after some brilliant work from Woods-Garness and swung in a vicious low cross which was turned into his own net by Simon Peddie.
They should have taken the lead four minutes later, but Woods-Garness somehow failed to make any contact with Rob King's low centre across the face of the goal.
But the former Sutton striker made amends seconds later as he hooked home a stunning effort from Hayles' long throw to put the Gulls 2-1 up.
It was his 12th of the campaign and put him one ahead of King as the Gulls top scorer.
Only a terrific point-blank save from Justham kept out Chatting's stab from six-yards from Ashley Dumas' low cross nine minutes from time.
Canvey (4-4-2): Jones; Hayles, Orlu, Bondon, Dumas; Miller, Dobinson, King, Hawes (Chatting 64); Woods-Garness, Dennis (Heale 84).
East Thurrock (4-5-1): Justham; Sammons, Peddie, Obaze, Stephen; Lawson, Parmenter (Mason 84), Ruel, Gilbey, Collins; L'Heureux (Burgess 84).
Echo MOM: Harrison Chatting (Canvey Island).