Alex is a centre/second row who was selected for the Rhinos scholarship in 2013 and was promoted to the Under-19s in 2017. He made his debut or the Rhinos first team in 2017, featuring against Wigan at the DW Stadium, and earned a new four year contract that season. Over 2018, he played eleven times for the Rhinos Under-19s, scoring three tries including one in the academy semi final 40-18 win over St Helens, but a year later he was one of six young Leeds players that benefited from a dual registration season with Featherstone Rovers. Sutcliffe made eighteen appearances throughout the Betfred Championship season, scoring sixteen tries, including Featherstone’s only try in the 24–6 Million Pound Game defeat to Toronto Wolfpack at Lamport Stadium. He was also recalled recalled back to the Rhinos first team for their Magic Weekend win over London Broncos, coming from the bench in the 24-22 win.
He studied at Royds School and played for Oulton Invaders, where he was part of the side who won the quadruple in 2015. He was selected to play in the School of Excellence (Leeds and Castleford) and played in the South Leeds City Challenge in 2011 and the Leeds Service Area in 2012.
He was born in Wakefield but lived in Australia between 2007 and 2008. His older brother, CJ, played for Wakefield Wildcats U19s and his sister has represented her county at Netball.