A collapsible stroller including a lockable hinge and a seat assembly pivotally mounted on the stroller frame. With the use of a seat strap attached to the seat assembly, the stroller can be collapsed using one hand. Pulling on the seat strap pivots the seat assembly to a position in which engagement surfaces on the seat assembly engage with the hinge latch of the lockable hinge. Engaging the hinge latch with the seat assembly unlocks the lockage hinge allowing the stroller to collapse.