Chris Brayford made three changes to the side that beat Kent Football United in mid-week, with Ria Collins, Pinja Piira and Allison McCann replacing Cheryl Anderson, Egle Trezzi and Lisa Holmback.
The tie started in a fairly cagey manner with both sides looking to gain control and neither creating a great deal.
Both sides traded a tame shot each before Sophie Le Marchand had the ball in the back of the net for the O’s in the 16th minute. However, the assistant referee cut any celebrations short by raising his flag for offside.
Ellie Stenning had a couple of chances just after the half hour mark, first dragging a shot wide, then curling an effort just past the far post.
Ten minutes later, Hayley Barton had a go at breaking the deadlock, but she also couldn’t find the target after she had shown some nice footwork to cut inside.
Cheltenham first real effort of note came just before the break. Kerry Bartlett found space inside the box and got a shot off that looked destined for the top corner, only for Latoya Smith in the O’s goal to produce a sensational save to keep the scores level.
The hosts also started the second half brightly with a couple of half chances, but nothing that overly concerned the Orient defence.
Just after the hour mark, the O’s took the lead. Le Marchand and McCann both had strikes which were turned away by Panniers in the Robins goal, the rebound then fell to Stenning who prodded home to break the deadlock.
A chance for a leveller for the hosts came and went when Leyre Bastyr did enough to put Bartlett off and force the Cheltenham forward to scoop the ball over.
In the final ten minutes, Orient had chances to make it more comfortable. First, Barton flashed one past the post after she had jinked her way into the box, then moments later Stenning was denied a second by the legs of Panniers.
Those proved to be the final chances as the O’s rode out the final minutes with ease to make history and secure a trip to Portsmouth in the second round.
Speaking after the victory, Orient skipper Danielle Griffiths expressed her delight at reaching the next round.
Looking ahead to the second round tie with Portsmouth, Griffiths said:
Orient: Smith, Collins, Griffiths, Bastyr, Piira, McCann, Ali, Barton (Cannon 89”), Le Marchand, Auguste, Stenning
Subs: Thomas, Hirst
Goals: Stenning 61”
Cheltenham: Panniers, Leask (Ellis 46”), Hallsworth, Dolloway (King 72”), Hitchcox, Bartlett, Martin, Bevan (Criddle 80”), Butler, Brown, Fensome
Subs: Wilkins, Butterfield, Rogers
Referee: William Mortimer