Early in his career he specialized in portraiture, especially paintings of female subjects, but during the first decade of the 20th century he also became one of the leading book illustrators in the United States as well a cover artist for national periodicals such as Scribner's Magazine, Collier's, and The Saturday Evening Post.

After 1914, Kimball began applying his talents increasingly to commercial advertising, which included designing theatrical posters for the film company Pathé and illustrating newspaper and magazine promotions for a variety of products.

"'High-lights'", he explained, "'that trickle down the face in a broken line striking the eyelids, the eyeballs, the corners of the eyes, a tiny speck on the lower lid, one on the teeth and one on the lips, give a look of perfect health.

'"[14] Despite his increasing freelance work in commercial art after 1905, Kimball continued to accept portrait commissions from private clients and to exhibit periodically in museums, galleries, and salons.

In a feature titled "Americans in Paris Salons", which was published in The Detroit Free Press on May 8, 1910, Douglas describes the painting of Madame Lemon, noting that "She wears a gorgeous Persian costume and is in a dancing pose—a filmy scarf falling from her raised arm.

[13] Between 1905 and the early 1920s, Kimball's artwork was used in newspaper and magazine advertisements throughout the United States to sell cameras, soaps, Torrington vacuum cleaners, men's and women's clothing, and a host of other products.

An early example of Kimball's illustrations in advertising is an upperclass family scene he drew specifically for Kodak, one that shows children unwrapping one of the company's box cameras next to a Christmas tree.

[18][19] The Detroit-based business Weil & Company, a large furniture retailer that also publicized itself as "outfitters" for men and boys, announced in newspapers in April 1911 that "one of America's most prominent illustrators" had agreed to furnish the store a series of original artwork for its advertisements.

"[20] One more example of Kimball's commercial work is a far more elaborate, full-color 1916 advertisement that includes his painting of a young woman and her attentive male companion to promote John H. Woodbury's facial soap.

Published in The Ladies Home Journal and in other periodicals, the "A skin you love to touch" advertisement offered readers a cake of soap with a print of Kimball's "new" painting "ready for framing" for "ten cents in stamps or coin" ($3 today)[21]

In December 1915, the New York trade publication The Moving Picture World announced the studio's intentions:Exhibitors [theater owners] everywhere have been loud in their praise of the one-sheets [posters] advertising Pathe Gold Rooster plays.

[24] One other commercial by-product of Kimball's artistic training and success as an illustrator and portrait painter was the development of his reputation nationwide as an expert in haute couture and in upper- and middle-class daily apparel for both men and women.

In a newspaper interview with columnist Marguerite Mooers Marshall in March 1912, Kimball shared his opinions about the basic deficiencies in the styling of women's clothing at that time, most notably in their excesses.

'"[25] As an artist whose commissioned oil portraits needed to remain appealing to viewers for generations, Kimball chose clothing for his female subjects that had simple, timeless lines.

'"[25] The following year, in a feature in The St. Louis Post-Dispatch highlighting his ideas about summer fashions, he recommended that more women should forego the norm of wearing heavier, fully enclosed shoes and enjoy instead the cooler comfort of sandals.

Kimball's standing in art circles and his popularity with the reading public had achieved sufficient status by 1907 that at least one man took advantage of his celebrity and for many months successfully impersonated the artist.

[28]The number of towns visited by the "imitation" Kimball and the duration of his fraud remain undetermined, although it was also reported that in the fall of 1907 he stayed briefly in Edneyville, North Carolina, where he "skipped out" on his $14 food bill ($475 today) and absconded with a shotgun and a prized hunting dog named "Shell".

Additional reports in North Carolina in 1908 state that the man, whose real identity remained unverified, also spent the summer and early autumn of 1907 in Hendersonville, but his travels prior to that are unknown.