Monaco have now won seven of their last 10 Ligue 1 fixtures, and are unbeaten in the league since the end of November.
After a bright start to events, Monaco took the lead in the 13th minute when Keita found the bottom corner of the net after meeting a low cross from Djibril Sidibe.
Dijon had to wait until early in the second period to create their first real chance of the match, and Kwon Chang-hoon's strike from outside the box forced a smart save from Danijel Subasic.
The visitors had another opportunity just past the hour when Julio Tavares met a cross from Oussama Haddadi, but the attacker's effort dropped wide of the post.
Monaco doubled their lead in the 69th minute when Fabinho converted from the penalty spot after the lively Thomas Lemar had been brought to the ground by Cedric Yambere.
The home side's third arrived in the 87th minute when Rony Lopes converted following a quick counter-attack, but Leonardo Jardim's side were not finished, and added a fourth though centre-back Glik in the second minute of stoppage time at the end of the 90 minutes.