The former Australia international scored five goals in 13 outings in his second spell at the club last season and is now eager to kick on with the Steelmen.
He said: "I have nothing but good memories from my time at Motherwell. The warmth from this club and what it gives me, and vice-versa, was a big attraction for me coming back.
"It is a family-orientated club and my family is ever-growing, with a new arrival on the way, so a lot of that was taken into consideration, as well as where we would be happy as a family and where I'd be happiest playing my football.
"I really enjoyed the end of last season and am hoping for some success here this season."