Robert Tonner is best known for his fashion doll designs and the creation of the Tonner Doll Company, Inc., which designs a number of original doll lines, such as the Tyler Wentworth and Antoinette series. In addition, Tonner Doll Company Inc. contracts with and designs for many major film studios. They have designed dolls for such contemporary films as Harry Potter, Spider-Man 3, and Twilight, as well as classic films, such as Gone with the Wind and The Wizard of Oz。In 1975, at the age of 23, Tonner was hired as the Personal Assistant to Don Sayres, a designer for Gamut, a sportswear company located in New York City. After three years with Gamut, Tonner accepted a position with fashion designer Bill Blass and was later asked to head the Blassport label. In 1983 Tonner launched his personal fashion label, "Robert Tonner for Tudor Square".

After leaving the fashion industry, Tonner joined the National Institute of American Doll Artists (NIADA). He served as Standards Chairman from 1991–1995 and was later elected President of NIADA 1995, a post which he held until 1997.

Tonner launched Robert Tonner Doll Design (RTDD) in 1991 with his partner Harris Safier. The first RTDD designs were introduced at the American International Toy Fair that same year. Backed by past connections within the NIADA and fashion design world, and the aggressive publicizing by Tonner’s partner Harris, RTDD saw exponential growth within the first few years. In 2000, RTDD was renamed Tonner Doll Company, Inc.

In 2006, Robert Tonner created the direct-marketing company, Wilde Imagination, which built a collectible fashion doll design business based on Tonner’s fictional character, Ellowyne Wilde. Wilde Imagination continues to market direct to the consumer with new collections featuring Evangeline Ghastly and licensed pop-culture dolls based on The Wizard of Oz (1939 film).

Recently, Tonner has returned to the world of fashion design with the introduction of the Robert Tonner 2010 Spring Collection which debuted on September 9, 2009, at the Metropolitan Pavilion in New York City.