He started his career at several clubs in Sweden, winning consecutive Allsvenskan titles with Djurgården before moving to France where he represented Rennes and Lyon. Källström won a range of domestic honours with Lyon and joined Spartak in 2012. He spent the second half of the 2013–14 season on loan at Arsenal, where he won the 2013–14 FA Cup after converting a penalty kick in the semifinal. Källström left Spartak in 2015 to join Grasshopper Club Zürich, where he had a 49 game long spell before ending his career at Djurgårdens IF together with close friend Andreas Isaksson.