A fall arrest lanyard includes a strap body having a fastening end, a securing end, and a relief portion, and restraint relief arrangement being actuated between a normal operated condition and a relief condition. The restraint relief arrangement includes first and second connectors spacedly affixed at the strap body to define the relief portion thereof between the first and second connectors. At the normal operated condition, the second connector is detachably connected to the first connector to shorten a length of the relief portion of the strap body. At the relief condition, the second connector is detached from the first connector, so that the relief portion is able to be fully extended to create a relief length for allowing the user to escape restraint when the user is restrained by the strap body.