Sammut has made three appearances for Scotland's Under-21 side and will join up with the Bairns squad for the start of pre-season on Wednesday after agreeing a year-long loan.
Manager Paul Hartley told the club website: “We are absolutely delighted to be able to bring a player of Ruben's pedigree to the club. “Ruben has been brought through and trained at an elite level having been with Chelsea from such a young age.
“I fully believe he has all the attributes to make a big impact in this league and I am really looking forward to working with him.
“He has massive potential and I think the opportunity for him now to experience first-team football will be of huge benefit to all parties."