The wingers late second-half goal saw Dover seal three points in Kent seven minutes from time.
Head Coach Justin Edinburgh made three changes to the side that drew 3-3 in the FA Trophy Quarter Final against Gateshead on Saturday.
Sam Ling made his first in an O’s shirt while Lamar Reynolds also started for the first time in the league. Dan Holman returned after being cup tied for the Gateshead fixture last weekend.
James Brophy made a late recovery from the same illness that kept Dan Happe out of the side this weekend and the winger started the afternoon on the bench.
Ebou Adams was alert to sweep away the danger from a free-kick that was headed goal-wards.
Dover’s Adebayo Azeez received the ball with his back to goal, under pressure from Sam Ling before the defender spread himself to block the eventual shot.
After a rather quiet start, the action suddenly picked up when Josh Koroma struck a sweet free-kick towards goal, only to be excellently denied by Mitch Walker.
From the resulting corner, Craig Clay rose highest and headed at goal but Nortei Nortey somehow managed to get a block in to deny the midfielder.
10 minutes remained of the first-half when Macauley Bonne nodded towards goal from a Koroma free-kick only to see the ball held well by Walker in the Dover net.
Bonne was involved again soon after, Clay won the ball back in midfield, and then found the run of Bonne who was through on goal but wasn’t able to keep his shot down as the best chance of the half went begging.
Dover had an injury time chance, Widdowson did well to tackle Ryan Bird but the rebound fell to Azeez who skied his effort as he closed in on Dean Brill’s net.
After the restart, Dover went close through Giancarlo Gallifuoco whose header forced Brill to dive down to his left to palm away.
Lamar Reynolds worked his way in to the centre and found Clay whose pass then found Dan Holman and allowed him to shoot on the turn, narrowly missing the target.
Again, Orient looked comfortable in possession when Jake Caprice collected the ball on the overlap from Koroma, but the full-back lashed at the shot and watched his effort clear the ground.
After 60 minutes, a Dover free-kick rebounded off the wall and dropped to Nortey who struck the ball against the post before Orient manged to clear the danger.
Koroma struck a free-kick over the wall and forced a save from Walker, almost identical to his one earlier in the game.
Orient came close to opening the scores when Dan Holman latched on to the end of Caprice’s through ball but was quickly closed down by Walker who pushed the ball to Reynolds whose first time shot bounced back off the post and out.
Marvin Ekpiteta was introduced in place of Reynolds for his debut after 78 minutes as Orient looked to turn their late chances in to a goal.
But it was Dover who grabbed the first goal of the game, Azeez found Mitch Pinnock out wide who tucked the ball in to the top corner of the net, as just seven minutes remained.
Orient pushed for a leveller late on with Josh Coulson firing wide from range, but Dover stood firm in defence to see out their one goal lead and secure the points.
DOVER: Walker, Passley (Okosieme 56), IIesanmi, Gallifuoco, Essam, Brundle (C), Pinnock, Bird (Parry 90), Nortey (Bellamy 70), Lokko, Azeez
SUBS: Jeffrey, Daniel
BOOKED: Essam (41), Gallifuoco (84)
GOALS: Pinnok (83)
ORIENT: Brill, Caprice (Harrold 87), Coulson (C), Widdowson, Ling (Brophy 66), Adams, Clay, Koroma, Reynolds (Ekpiteta 78), Holman, Bonne
SUBS: Grainger, Lawless
ATTENDANCE: 1,346 (299)
REFEREE: Christopher O’Donnell