The 24-year-old initially joined Lille on loan last year before signing a permanent deal until 2020 in May.
His future was in doubt last month when he learned he was no longer required by new Lille coach Marcelo Bielsa.
Despite interest from several clubs, Sliti opted to join Dijon, who have the option to sign him on a permanent deal when his loan expires next year.
"It's true I received some offers but there are a lot of things that motivated me to come to Dijon," Sliti told the club official website.
"The first, and most importantly, is that the coach called me.
"It's a crucial year for me with the World Cup in mind, so it's important to feel confident and see that the coach is counting on you.
"I checked on the club, and I had very good feedback. A healthy atmosphere prevails within the club. It's like a family. I am very happy to be part of this family."
In his sole campaign in the top flight, Sliti played 18 games for Lille last season, scoring once.
"I had a somewhat mixed year, but honestly, that served me well for experience," said Sliti.
"I learned a lot, and today I can tell you that I am really happy and I look forward to playing football again.
"I think that here is the ideal place to find this football pleasure and I cannot wait to meet my new teammates."
Sliti, who began his career with Sedan before moving to Paris FC in 2013, has won 12 caps for his country and scored three goals.
He represented his country at the 2017 African Cup of Nations - where he played all four matches as Tunisia exited the tournament in the quarter-finals.
Tunisia international midfielder Naim Sliti has joined French side Dijon on a season-long loan from rivals Lille.