In the 1992 Summer Olympics, he competed in the 4 × 200 metre freestyle relay along with Christer Wallin, Anders Holmertz and Tommy Werner.

In the 1996 Summer Olympics, Frölander again finished second in the 4 × 200 metre freestyle relay with the Swedish team.

The highlight of his career was when he won the gold in the 100 metre butterfly event at the Sydney Olympic Games in September 2000.

A couple of months earlier, he twice broke the world record in the men's 100 m butterfly (short course).

[1] At the 2012 Summer Olympics, Frölander, at the age of 38, posted a 52.47 in the opening heats of the 100 m butterfly, less than 1 second slower than top qualifier Chad le Clos, but 0.12 seconds too slow to advance to the semifinals.