Fremantle Dockers midfielder Nathan O'Driscoll has bravely shared his mental health struggles on social media, revealing he has been close to suicide three times.

The 23-year-old, who has played only twice this season, opened up on Instagram about his depression and anxiety. He said recent weeks have been especially tough after the death of someone close to him.

"I'm sharing this because speaking up matters," O'Driscoll wrote. "From the outside, it might look like I have everything, but what's going on internally can be a very different story."

The post quickly drew widespread support. His sister Emma, a Dockers AFLW player, expressed pride in him. His brother Aiden called him "the best big brother anyone could ask for." Dockers teammates including captain Alex Pearce also offered support.

O'Driscoll has not played since round three. He said he was hesitant to share his story, but felt it was the right time given recent focus on mental health in the league.

Fremantle executive general manager Joe Brierty praised O'Driscoll for speaking openly. The club will continue supporting the midfielder.