The "Ghayal" actor in February had announced that the film will release on July 19.
Sunny on Tuesday morning tweeted: "The wait may have become longer but it will be worth it! 'Pal Pal Dil Ke Paas' will now release on September 20."
Apart from his son, the film marks the debut of another new face Sahher Bambba. She will be seen playing Karan's love interest in the movie.
Also READ- Father's Day 2019: Sunny Deol's son Karan Deol pens down HEARTFELT poem for him
The title of the film is taken from veteran actor Dharmendra's famous song "Pal pal dil ke paas" from the movie "Blackmail", which released in 1973.