Thumbsucker (2005) was his feature-film directorial debut, for which he also created the film posters. In 2007, Mills filmed the feature-length documentary Does Your Soul Have A Cold?, which explored the issues around the introduction of anti-depressants to Japanese culture. The film premiered at SXSW Festival and was part of IFC's documentary film series.[10]
In 2010 he directed the Focus Features independent comedy Beginners which starred Ewan McGregor, Mélanie Laurent, and Christopher Plummer. The film is both a romantic comedy and a film about a son reflecting on his memories of his father. Amy Taubin of Film Comment praised Mills, calling it a breakthrough, writing, "Mike Mills treats love and loss with a disarming tenderness and a refusal of sentimentality that make Beginners, his second feature, something of an anomaly among male identity flicks."[11] Plummer went on to win the Academy Award for Best Supporting Actor for his performance.[12][13]
His next feature film was the A24coming-of-age drama 20th Century Women (2016) which starred Annette Bening, Greta Gerwig, Elle Fanning and Billy Crudup.[14][15][16] The film had its world premiere at the New York Film Festival, and was released on December 28, 2016.[17][18]The Hollywood Reporter film critic David Rooney praised the film saying, "Mills uses some of the same devices as Beginners to illuminate his characters' cultural formation, notably historic montages of their birth years or backgrounds prior to coming together. And he also glances ahead to their future lives, after the arc of the movie. But the quilting is more seamless here because the eccentricities are so integral to the writing and performances."[19]
He has released some of his art/documentary photography works with the two books, Gas Book 11 (2003) and Humans (2006). In 2009, the Berlin-based culture magazine 032c devoted an issue to Mills. For the occasion Mills was interviewed by Nick Currie, best known for his work as Momus, in a piece called "Getting Through the New Depression".[20] In 2019, he directed the short film I Am Easy to Find starring Alicia Vikander, which accompanied the album of the same name by The National.[21]
Mills' latest directorial feature film was the 2021 black-and-white drama film entitled C'mon C'mon starring Joaquin Phoenix, Woody Norman, and Gaby Hoffmann. The film was distributed by A24 and had its world premiere on 2 September 2021 at Telluride Film Festival.[22][23] Clarisse Loughrey of The Independent praised Phoenix's performance noting it as "a career best", and further applauded Mills as "a master of intimate, unforced emotion and the kind of simple wisdom that always sounds best when it’s coming from the minds of children".[24]
Mills' mother died of brain cancer in 1999. Six months after she died, his father Paul came out as gay at the age of 75 and after 45 years of marriage. Five years later, his father died of cancer.[6]
Mills is married to fellow artist and film director Miranda July,[28] with whom he has a child, born in February 2012.[29][30]