Bradley Fewster had given the hosts an 18th minute lead from close range, before being forced to see out the final period a man light when William Boyle was shown a second yellow card 16 minutes from time.
Moments later Orient then made the most of the dismissal as Lloyd James crashed home an equaliser from the edge of the area on the 76th minute to claim a point.
Looking to bounce back from back-to-back defeats over the Easter weekend, player-manager Kevin Nolan made two changes for the trip to York.
Defender Shaun Brisley returned in defence having missed the defeat to Hartlepool with a dead leg, while the O’s also welcomed back Jobi McAnuff following international duty with Jamaica.
Calaum Jahraldo-Martin also returned to the squad after being away with Antigua & Barbuda, as the Hull loanee was named on the substitutes bench.
Ahead of kick-off the O’s sat two points outside the Play-Off places, but within 20 seconds of the match starting Orient goalkeeper Alex Cisak was forced into parrying away a powerful strike before Michael Coulson saw his follow up blocked by Nicky Hunt.
The hosts had started the much better of the sides, and Alessandra nearly had a second opportunity five minutes later when Shaun Brisley missed a header just inside the O’s half, but the defender made a fantastic recovery to thwart the striker as he shaped up to shoot inside the box.
With 18 minutes played York then deservedly took the lead when former O Luke Summerfield delivered a dangerous cross into the box which was emphatically swept home by Bradley Fewster.
Having fallen behind Orient then saw a well worked move down the left present them with a chance to equalise, but Kevin Nolan’s drilled ball across goal was just missed by Ollie Palmer at the far post.
York then responded with a chance of their own moments later when full back Femi Ilesanmi’s high lofted ball back into the box was flicked on by Scot Bennett, but Cisak was able to keep hold of his effort.
The O’s had yet to really trouble Scott Flinders in the York goal throughout the first half, but with just over 10 minutes remaining Palmer almost claimed a fortuitous equaliser when the goalkeepers kick rebounded back off him only to fortunately drop back into the hands of Flinders.
Palmer’s chance appeared to spur the visitors on and winger Jobi McAnuff was denied by a spectacular save a minute later when his low strike across goal was wonderfully touched round the post.
As half time loomed it looked as though the O’s would be going into the break a goal down, but with one minute of normal time remaining they had a brilliant opportunity to level when referee Trevor Kettle awarded a penalty after William Boyle had handled inside the area.
McAnuff stepped up to take the spot-kick, but was unable to convert from 12 yards as his effort crashed back off the foot of the post before being cleared.
Deep into first half stoppage time York then had a penalty appeal of their own when James Berrett went down under the challenge of Peter Ramage, though instead of a penalty being awarded the midfielder was shown a yellow card for simulation as the O’s went into the break a goal down.
Following the interval Orient returned for the second half unchanged, and with 55 minutes played Jay Simpson hooked a volley over the bar having latched onto a Palmer flick-on with his back to goal.
The O’s were definitely improved following the break, and following a strong period of pressure player-manager Nolan was denied his first goal for the Club when his header was parried away before Simpson’s rebound attempt was blocked.
Lloyd James and Calaum Jahraldo-Martin were then introduced for the final 25 minutes as they came on for Nigel Atangana and Sean Clohessy, who handed the captain's armband to McAnuff. Within a minute of his introduction James delivered a wonderful cross for Ramage who saw his header brilliantly tipped over by Flinders.
The Minstermen goalkeeper produced another terrific stop two minutes later when a O’s corner led to Jahraldo-Martin teeing up McAnuff on the edge of the area, but despite the winger’s effort appearing destined for the top corner Flinders somehow got a touch to divert it over the bar.
With just over 15 minutes remaining York were then reduced to 10 men when just like at the end of the half, they saw a penalty appealed waved away when Boyle, who had already been booked for conceding the O’s spot kick, went down and was shown a second yellow card.
It then took Orient a minute to exploit their man advantage as the impressive James levelled the score with a rasping volley from the edge of the area which found a way through a number of bodies to beat Flinders.
Armand Gnanduillet then came on for the final 10 minutes in place of Palmer who had put in a tireless display up front, but having just taken to the field York nearly edged back in front when Fewster saw his header bounce off the top of the crossbar before going behind for a goal kick.
Nolan and Gnanduillet were then denied by two pieces of good defending, and with a minute of normal time remaining York's Luke Hendrie saw his powerful strike from the edge of the area parried behind by Cisak for a corner.
Despite six minutes stoppage time being shown neither side were able to claim a winner as the O's were forced to settle for a point despite a dominant second half display.
YORK: Flinders, Hendrie, Winfield (C), Boyle, Ilesanmi (Galbraith 48), Berrett, Bennett, Summerfield, Coulson (Oliver 70), Alessandra, Fewster
SUBS: Ingham, Dixon, McEvoy, Riordan, Hyde
GOALS: Fewster (18)
BOOKINGS: Boyle (44), Berrett (45+4), Alessandra (68), Galbraith (90+1)
SENT OFF: Boyle (74)
ORIENT: Cisak, Hunt, Brisley, Ramage, Binnom-Williams, Clohessy (C) (Jahraldo-Martin 66), Atangana (James 66), Nolan, McAnuff, Simpson, Palmer (Gnanduillet 80)
SUBS: Gregory, Pollock, Moore, Turgott
GOALS: James (76)
BOOKINGS: McAnuff (83), Ramage (87), James (90+2)
REFEREE: Trevor Kettle
ATTENDANCE: 3,234 (656 Orient supporters)