At around 6.50pm, police believe a Honda Civic struck the child on Charnwood Place.
The toddler was rushed to Dumfries and Galloway Royal Infirmary but was pronounced dead shortly after.
The 54-year-old man driving the car was uninjured.
Police are appealing for any witnesses to the incident to get in touch.
Sergeant Bob McNay, from Police Scotland’s road policing unit, said: “Our thoughts are with the child’s family at this time, following their tragic loss.
“The investigation into the incident is ongoing and we are asking for anyone who was in the area and witnessed the events to please come forward.
“We are also keen to speak to anyone who may have CCTV overlooking the Charnwood Place area to get in contact, as they may be able to assist our inquiries.
“If you have any information, please contact police on 101, quoting incident 3597 of April 2, 2021.”