The winger will stay with the Lilies until the end of the season, and will be keen to showcase the skills that earned him a move to the Royal Blues in the first place.
Sam was in action the very same day as he came on as a late substitution in the side's 2-1 friendly win over VfL Bochum.
Time to work his way up again
Following what has been a rotten two-and-a-half year spell with Schalke, Sam is desperate to get his career back on track where he has been frozen out of late.
After being suspended from the team along with Kevin-Prince Boateng, game-time has been a rarity - having featured for just 164 minutes in the last season-and-a-half.
Before making the move to Gelsenkirchen, Sam was at the peak of his powers and a German international while with Bayer Leverkusen.
He finished his final season with the Werkself, he managed eight goals and seven assists in an impressive 20 games. It's little wonder then that Schalke signed him.
Having previously spent time with both 1. FC Kaiserslautern and Hamburger SV, this will be the 28-year-old's fifth professional club.
Frings and Sam have their say
Darmstadt head coach, Torsten Frings spoke to the club website when the news broke: "I am unbelievably happy that Sidney Sam wants to come along this way with us."
The manager then explained some of the new arrival's key skills, "He is a quick, technical adept attacker, who brings a huge amount of experience."
Sam himself said, "I'm really excited with this challenge. My goal is, of course, to get game time in the Bundesliga gain and to secure the Lilies' Bundesliga status."