A bicycle hydraulic actuating device is provided with a housing, a non-linear piston and an operating member. The housing defines a chamber and has a fluid outlet. The non-linear piston is movably disposed in the chamber along a non-linear movement path between a first position and a second position. The operating member is operatively coupled to the non-linear piston so as to move the non-linear piston within the chamber between the first position and the second position in response to movement of the operating member.