A wheelchair braking device providing a braking action that automatically disengages when an occupant is seated in the wheelchair. The braking device includes a support structure to which a sensing lever is pivotably mounted and to which a braking arm is slidably mounted. A biasing element is coupled to the braking lever to bias the braking arm in a first direction relative to the support structure and into engagement with a wheel of the wheelchair, thereby inhibiting rotation of the wheel. The sensing lever and braking arm are interconnected such that the biasing element operates through the braking arm to bias the sensing lever in an upward direction against the wheelchair seat. The interconnection between the sensing lever and braking arm causes the braking arm to disengage from the wheel when the sensing lever rotates in a downward direction.