Her previous best individual World Cup finish was a second place at a sprint event on 1 January 2013 held in Val Müstair, Switzerland during Tour de Ski.

In the 2018–2019 season, Østberg won the Tour de Ski with a record winning margin of 2 min 42.0 seconds down to Russian Natalya Nepryayeva.

[3] She was forced to sit out seven World Cup races, before making her return in late December,[4] where she finished third overall in the 2019–20 Tour de Ski.

[5] In March 2020, she suffered a stress fracture in her left heel, and missed the last two World Cup races of the season.

The NSF head physician, Øystein Andersen, said in a press briefing that the medical results from the three World Cup races Østberg had taken part in, showed that she couldn't handle a tougher schedule.