Drake says the last time his pops, Dennis Graham, was allowed in Canada ... Drake's career was just taking off, but after a 15-year wait ... he's happy to say daddy's home!!!

Drake hopped on IG Monday night to boast both of his parents were together under one roof on Canadian soil ... quite the milestone. He said, "First time in over 15 years they let the OG back into Canada thank you to everyone that helped us out @therealdennisg."

In a separate flick, Dennis was seen diving right into grandfather mode with Drake's 6-year-old son Adonis ... a little breakfast toast makes school that much more enjoyable!!!

Whether or not he's physically there, DG always wants the best for his fam. He shared some of his fatherly advice recently, when he told us it was wise for Drake to stay out of online debates surrounding the Israel-Hamas war.

Drake's gotta be soaking up this family time -- he and J. Cole are set to embark on their "It's All a Blur -- Big As The What?" tour.

For what it's worth ... they won't be stopping in Canada.