Internationally renowned Western Australian artist Matt Doust has died in Los Angeles.

Doust, who was known for his highly refined portrait oil paintings, died after reportedly having a seizure.

The 29-year-old had a strong following among art collectors both nationally and internationally, including Hollywood actors Jim Carrey and Mickey Rourke.

Doust, who was born in the United States but grew up in Perth, had rapidly become one of WA's most prominent artists.

The LA-based artist was a finalist in the 2011 Archibald Prize with a portrait of model and actress Gemma Ward.

Doust's last Perth exhibition, Unravel, was held at the Venn Gallery in 2012.

The Thinkspace Art Gallery in Los Angeles was due to hold an exhibition featuring his new work starting on September 7.

"The world lost an amazing soul last evening. Our good friend Matt Doust sadly passed away last evening at the young age of 29 years old," the gallery said on Instagram.

"He had just completed work on his debut US solo show and we were all so looking forward to his opening at Thinkspace.

"We are all shocked by this sudden loss and coming to grips with the gravity of it all."

A press release on the gallery's website describes Doust's portraits as "undeniably beautiful" and "haunting".

"[Doust's] dramatic human landscapes tap in to the subtle revelations of physical expression, drawing the viewer's attention to the subject's minutest details," it says.

"At times voyeuristic, these larger-than-life portraits are both alienating and intimate.

"Doust draws on our anxiety and fascination when faced with the other in this unfamiliar proximity and scale, forcing monumental disclosures of intimacy upon us."

An autopsy is being conducted to determine the cause of death.