A first half strike from the Southend forward proved enough for the victory, Dale Gorman and Matt Harrold went close either side of the break but were unable to hit the back of the net.
Orient got the game started and had the first attempt on goal through Dale Gorman who dragged his shot from range wide of the target.
Following an end-to-end opening 10 minutes, a long Southend ball forward looked to have breached the O’s defence as the forward approached goal, but ‘keeper Sam Sargeant rushed off his line to smother the danger.
Sargeant then released James Alabi on the O’s attack, the forward had his back to goal before he turned and crossed for Jayden Sweeney at the back post, but the youngster’s header bounced just wide of the target.
Alabi was in behind the Southend defence once more, this time the forward took the shot on himself but fired over the target.
The visitors took the lead after 15 minutes when a cross from the right was chested beyond Sargeant from close-range.
It could have been two soon after, but Dan Happe was present to block the shot from a well-timed cut back inside the Orient penalty area.
Southend enjoyed plenty of possession in the Orient half and forced Sargeant in to an excellent dive to tip the ball over the bar from a long-range effort.
With 15 minutes left to play, Gorman’s cross-field pass to Hector Kyprianou saw the midfielder skip past his man and square the ball to Alabi whose shot missed the target by inches.
Orient ended the second-half on top, Matt Harrold’s lay off found Gorman who whipped an effort whiskers passed the post in what proved to be the final effort of the half.
The two sides were unchanged after the break and Orient picked up where they left off. Gorman’s corner found the head of Harrold who could only hit the post before Alabi’s rebound was blocked away from danger.
The O’s were certainly on top in the second half and restricted the visitors to shots from range, as their skipper fired low and wide after a quick counter attack.
Gorman and Harrold linked up once again when the latter’s flick on set the midfielder through on goal, but for the Southend ‘keeper who made a last second challenge on the ball to deflect the danger.
Unable to force an equaliser, Orient continued to push forward in the closing stages as Lawless’ long ball forward found Jaedon Philips who turned but could only fire over from his left footed attempt.
ORIENT: Sargeant, Fleming, Hall (Kyprianou 3), Happe, Ogie, Benyoucef (Sivi 75), Gorman, Lawless, Sweeney, Harrold (Hammond 75), Alabi (Philips 55)
SUBS: Janata, McClenaghan