Billy Knott, Billy Clarke and Jon Stead were all on target for the Bantams.
Orient had equalised through David Mooney in the 74th minute, but lost Chris Dagnall to a red card soon after and Bradford took advantage with two quickfire goals.
James Coppinger’s equaliser saw Doncaster Rovers draw 1-1 at Crewe.
On-loan teenager Uche Ikpeazu had given Crewe the advantage.
York City grabbed a point at high-flying Plymouth in League Two.
Jake Hyde pounced in the closing stages for the equaliser, after Reid had put the hosts in front on three minutes.
In the Conference, Halifax Town got back to winning ways with a 2-0 win over Alfreton Town.