King, 33 has signed for the Bramall Lane club unti the end of the season and could make his debut for his new club at home to Preston North End this Saturday at Bramall Lane (3pm kick-off).
Blades boss David Weir told sufc.co.uk; "Marlon is vastly experienced and has scored goals throughout his career, many of which that have come in the Championship. We have been lacking someone with his experience and knowhow and his presence will take the pressure off the younger lads, whilst giving everyone a lift. Marlon has recently played international football so although he hasn't played at club level this season we will be looking to introduce him as quickly as possible."