It is the third chapter in the film franchise based on E.L. James' Fifty Shades novels.
"Expanding upon events set in motion in 2015 and 2017's blockbuster films that grossed almost $950 million globally, the new installment arrives for Valentine's Day 2018," said a message accompanying Sunday's one-minute clip.
The preview, which has already gotten more than 1.5 million views since it was posted, shows Christian and Anastasia getting married and Anastasia adjusting to her new lifestyle.
Fifty Shades Freed is directed by Fifty Shades Darker's James Foley. The first movie in the series was Fifty Shades of Grey, which was helmed by Sam Taylor-Johnson.