Otto earned a place on the European Tour for 2000 by graduating from the Challenge Tour, but struggled to establish himself on the tour. In 2003, while splitting time between the European and Challenge Tours, he finished tied for tenth at The Open Championship in his major championship début and went on to finish 73rd in the European Tour Order of Merit. In 2008, again playing with limited European Tour status, he won the Italian Open and finished 37th on the Order of Merit. The win gave him full membership for the first time since 2004; this he maintained through the 2017 season, winning the 2011 South African Open Championship and the Italian Open again three years later.
Including the South African Open win, Otto has won 14 times on the Sunshine Tour since 1999.