The settlement was originally known as Prairie Valley when the Houston and Texas Central Railroad arrived in 1872.

The community's shallow wells were unable to pump the adequate amount of water needed to extinguish the blaze.

Throughout the latter half of the twentieth century, Wilmer continued to grow, but at a much slower rate than other communities in Dallas County.

[8] With 3,393 residents as of the 2000 census, Wilmer is currently one of the smallest incorporated cities in Dallas County.

As of the 2020 United States census, there were 4,974 people, 1,576 households, and 1,095 families residing in the city.

[13] The shipping facility, built by AUI Contractors, Prime Rail Interests and Halff Associates, was a 70 million U.S. dollar project.

After Union Pacific (UP) chose Wilmer for its global intermodal facility, the City attracted Fortune 500 companies like Unilever, Procter & Gamble, Whirlpool, Ace Hardware and Medline.

From 2005 to 2006[27] to 2008–2009 W. W. Bushman,[28][29] B. F. Darrell,[30][31] J. N. Ervin,[32][33] and Whitney M. Young elementary schools served sections of Wilmer.

[51] The district was scheduled to Wilmer Hutchins Elementary School in an area within the City of Dallas in 2011.

[55] A new DISD elementary school in Wilmer, named after Eddie Bernice Johnson, opened in 2020.

Meeting agendas, public hearings, legal notices, and city ordinances are published in the official newspaper, Ellis County Press.