A surgical stapling instrument including a stapling end effector configured for unilateral sealing of tissue. The stapling end effector includes an anvil assembly, a cartridge assembly coupled to the anvil assembly such that stapling end effector is movable between open and closed positions; and a clamping member slidably disposed about the anvil assembly and the cartridge assembly between an initial position in which the stapling end effector is in the open position and subsequent advanced positions in which the stapling end effector is in the closed position. The clamping member includes a substantially “C”-shaped cross-section with a leading edge. The leading edge includes a blade portion positioned outwards of the anvil and cartridge assemblies.