James Heath Kitchens, 30, is accused of intentionally striking Brittany Rhea Phillips, 26, in his car on a road in Oktibbeha County, Mississippi, on Saturday.
The mum-of-two was rushed to OCH Regional Medical Center following the incident on Riviera Road around 8pm, where she was pronounced dead, reports Magnolia State Live.
Police say Brittany Rhea's death came about following a "domestic incident", though no further details were provided.
Kitchens worked as a police officer in Tupelo, Lee County, for just over a year until May 2020, according to WTVA.
A GoFundMe page, launched by friend Kelley Miah to help mum Stacie pay for funeral costs, describes Brittany Rhea as a "beautiful soul inside and out" who "knew how to bring a smile to everyone's face".
"She was robbed of life too soon and her family would appreciate your support during this traumatic time."
It adds that her daughter was seven and her son - who Kitchens is understood to have fathered - was just 10 months.
Brittany Rhea owned an online boutique called Couturhea and a shop called Beauty Perfected.
Writing on Facebook, a photographer for Belmont Images Magazine, who had known the tragic mum for 10 years, said she "leaves behind a lot of fond memories"
"She ultimately travelled the world doing what she loved to do. She will be missed," he added in his tribute.
Kitchens is being held at Oktibbeha County Jail on a $25,000 bond.