Longmire is based on the Walt Longmire Mysteries novels by best-selling author Craig Johnson, adapted for television by John Coveny and Hunt Baldwin.

Despite becoming A&E's highest-rated original drama series with almost 6 million viewers per episode, the network cancelled Longmire after its third season in 2014, reportedly because its older-skewing audience was unappealing to advertisers.

Three months after A&E's cancellation, Netflix picked up Longmire for additional seasons, choosing it specifically because of its strong appeal to a specific segment of the audience, in contrast to A&E's reasoning.

Although the story is set in northern Wyoming, the series was actually filmed in several New Mexico locations, including Santa Fe, Eagle Nest, Espanola, Red River, Las Vegas (New Mexico), and Pecos, with Buffalo, Wyoming used for some scenes set in the fictional town of Durant.

During 2013 production, massive wildfires broke out in the Valles Caldera National Preserve, with the Prescott Fire Department's Granite Mountain Hotshots helping prevent destruction of the area used to film Walt's house; nineteen of the twenty Hotshots later died battling the 2013 Yarnell Hill Fire in Arizona, and the show honored them in the season two finale's closing credits.

Interior filming for later seasons took place at Garson Studios on the campus of Santa Fe University of Art and Design in New Mexico.

Australian actor Robert Taylor was cast first in the lead role of Sheriff Walt Longmire, with the rest of the main cast—Katee Sackhoff, Bailey Chase, Cassidy Freeman, and Lou Diamond Phillips—announced in subsequent casting rounds starting in February 2011.

The Longmire pilot's teleplay, written by Hunt Baldwin and John Coveny, was nominated for an Edgar Award by the Mystery Writers of America in 2013, and makeup artist Steve La Porte was nominated for a Makeup Artists and Hairstylist Guild Award for Best Special Makeup Effects in 2014.