In the 2005–06 season, Riggott became the first choice central defensive partner for Gareth Southgate, in a successful season which saw the club reach the UEFA Cup final he stood out and was generally regarded as being one of the outstanding players for Middlesbrough during the season. In the UEFA Cup semi final against Steaua Bucharest, Boro found themselves 3–0 down on aggregate and needing four goals to get through to the final. Riggott crucially scored the third of the four needed as Middlesbrough miraculously reached the final.