Since 2022, they have been accused of committing assault, burglary, disorderly conduct, harassment, and grooming of minors, resulting in multiple widely publicized arrests, citations, and restraining orders.

In 2010, Miller portrayed the lead of Beware the Gonzo and had a supporting role in Every Day, both of which premiered at the Tribeca Film Festival.

They next appeared in the BBC Films drama We Need to Talk About Kevin (2011), alongside Tilda Swinton and John C. Reilly, which was adapted and directed by Lynne Ramsay from American author Lionel Shriver's 2003 novel of the same name.

In the 2012 film adaptation of the novel The Perks of Being a Wallflower, Miller played Patrick, alongside Logan Lerman and Emma Watson.

[25] Miller has been credited with singing, drumming and percussion on musical recordings by the band Sons of an Illustrious Father as early as 2011.

[34] In 2020, they reprised the role of the Flash for a cameo appearance in the Arrowverse crossover event, Crisis on Infinite Earths.

In December 2020, Miller portrayed Trashcan Man in the Paramount+ television miniseries The Stand, based on the Stephen King novel of the same name.

[43][44] Having expressed an interest in "kissing boys" at a young age,[45] Miller said, "The way I would choose to identify myself wouldn't be gay.

"[17][46] In 2018, Miller showed support for the #MeToo movement and revealed a personal experience concerning a Hollywood producer and a director, both of whom were left unnamed: "They gave me wine and I was underaged.

'"[40] In November 2018, Miller announced that they were in a polyamorous relationship with multiple people, including their bandmates in the rock band Sons of an Illustrious Father.

Tokata Iron Eyes, an associate of Miller, later referred to their bulletproof vest as "a fashionable safety measure in response to actual attacks and received death threats.

"[4] On January 27, 2022, Miller posted a video on Instagram that seemed to threaten members of the Ku Klux Klan operating in Beulaville, North Carolina.

[48] In response, the Southern Poverty Law Center reported no knowledge of recent Klan activity in Beulaville.

"[12] On April 6, 2020, a video surfaced in a since-deleted tweet that appeared to show Miller choking a woman and throwing her to the ground.

The video was confirmed by Variety to have taken place at Prikið Kaffihús, a bar in Reykjavík, Iceland, that Miller frequents when in the city.

During their arrest, Miller said that they were being "unlawfully persecuted" and, after members of the police misgendered them, accused the officers of intentionally committing a hate crime.

[60] On April 19, Miller was again taken into custody for second-degree assault by Leilani Estates Subdivision police authorities in Pāhoa.

According to Midi Libre, they were arrested for throwing a chair, which hit a 26-year-old woman and left a half-inch cut on her forehead, after being told to leave during a private get-together.

[62][63] Within hours of this second arrest, Miller pleaded no contest to the karaoke incident and was fined $500 for disorderly conduct by judge Kanani Laubach.

[64][65] In June 2022, the Standing Rock Sioux tribal court issued a temporary order of protection against Miller on behalf of 18-year-old activist Tokata Iron Eyes.

[70] Iron Eyes's parents later attempted to obtain a permanent order of protection against Miller, but it was eventually dismissed.

Iron Eyes defended Miller by referring to the incident as "a catty comment" and a part of "queer dialogue"; she called the allegation of abuse "homophobic".

Shortly before the harassment prevention order was granted in June, the mother stated, Miller arrived at the family's house dressed as a cowboy and attempted to buy horses for the child.

[77][78] A day before the scheduled hearing, Miller accepted a plea deal, pleading guilty to trespassing, with the burglary and petit larceny charges being dropped.

[80] Miller was handed 12 months probation by Judge Kerry Ann McDonald-Cady at Bennington County Superior Court, Vermont.

Miller told the court they believe they can comply with the stipulations of the one-year probation, which included no contact with the victims, continuing their mental health treatment, random alcohol screenings, and not being convicted of a criminal offense, among others.