The firm was founded in July 8, 1952 as O'Gorman, Nattier & Anderson after its three initial partners who were all American attorneys.

The firm changed its name to Anderson & Mōri in 1991 following the departure of partner Richard Rabinowitz, who joined several other Anderson Mori attorneys to form the firm of Tōzai Sōgō in 1994.

The firm adopted its present name after merging with Tomotsune & Kimura in 2005; Tomotsune & Kimura was itself an offshoot of the law firm founded by Toshiro Nishimura in 1967, which would eventually become Nishimura & Asahi.

Following the collapse of Bingham McCutchen in 2014, 50 of the 60 lawyers at Bingham's Tokyo office joined Anderson Mori in 2015, with the remainder joining the Tokyo office of Morgan, Lewis & Bockius.

The firm's Asian offices focus on supporting Japanese clients abroad.