Kenny Jackett opted to make no changes to his side that conceded late on at Rochdale, although Paul Smyth made a return to the bench following a toe injury.
The visitors, who had been in great away form, made just the one change, as Louis John came in to replace Coby Rowe.
It was the EFL newcomers who started brightly too, forcing The O’s to soak up a lot of early pressure, with free-kicks and corners creating an aerial battle early on.
Hearts were in the mouth, as a corner nearly squirmed its way over the line in the Orient box, but Lawrence Vigouroux was there to calmly scoop it up.
Orient grew into it and started to have a bit more say on the game, but a defensive mistake opened up a golden chance – which they took with both hands.
Alex Mitchell’s cross-field ball wasn’t controlled cleanly by Shad Ogie, with Sutton’s Isaac Olaofe racing into capitalise, striding forwards before firing an unstoppable strike beyond Vigouroux.
The O’s were slow initially to respond, but soon restored parity, with Theo Archibald back on the scoresheet.
A well worked long throw from Tom James was flicked on by Harry Smith, with Theo Archibald rushing in to make no mistake from close range, and send the stadium crazy.
The O’s continued in the ascendency, and almost took the lead when Aaron Drinan anticipated a weak backwards header, and found himself one on one with Bouzanis.
He had to take the header first time from distance though, and steered it just wide of the post.
The O’s picked up where they left off, and raced into a lead almost instantly.
With Theo Archibald picking the ball up on the left hand side, his early cross caused confusion in the Sutton backline, with the ball dropping inside the penalty area.
Harry Smith didn’t need to be asked twice, stooping to head home, and knee sliding his way to the Justin Edinburgh West Stand.
It almost got better too, when Archibald again aiming to be provider – his teasing cross met at the back post by Kyprianou, with his first time strike hitting the bar, denying him his first goal of the season.
With the game in the balance, it needed a moment of brilliance to set The O’s apart even more – and it was the big number nine who obliged.
This time, however, not with his head, but rather a sublime left footed volley, caught perfectly from the edge of the box.
Nestling into the top corner, Smith’s volley saw the crowd erupt once more, as The O’s pushed closer towards a big three points.
And this was finalised in stoppage time, as a quickly taken corner from Theo Archibald found Tom James unmarked in the box, who was able to fire home smartly from 12 yards.
The goal capped off a wonderful second half performance, which saw The O’s come from behind to push themselves up to 6th place, ahead of two away trips next week.
Leyton Orient: Vigouroux, James, Clay, Smith, Kemp, Archibald, Mitchell, Beckles (C), Drinan (Smyth 86′), Kyprianou (Pratley 82′).
Subs unused: Byrne, Wood, Happe, Thompson, Sotiriou.
Goals: Archibald 29’, Smith 46’, 82′, James 90+4
Yellows: Ogie 69’
Sutton United: Bouzanis, Goodliffe, John, Ajiboye, Randall, Eastmond (C), Olaofe, Kizzi (Barden 67’), Milsom, Bennett (Bugiel 56’), Smith.
Subs: House, Barden, Wyatt, Davis, Korboa, Wilson.
Goals: Olaofe 18‘.
Yellows: Ajiboye 77′, Eastmond 88′.