In the 2007–2008 season, Lepistö began competing entirely on the senior level. She won the bronze medal at the 2007 Nebelhorn Trophy and placed 4th at the 2007 Finlandia Trophy. She then debuted on the ISU Grand Prix of Figure Skating circuit. At her first event, the 2007 Skate Canada International, she won the short program but dropped to 7th overall after the free skate. She placed 5th in her second event, the 2007 NHK Trophy. Lepistö won the 2008 Finnish Championships and went on to the 2008 European Championships where, competing there for the first time, she won the bronze medal. She then placed 8th in her World Championship debut.