The 25-year-old agreed to a four-year deal with the Mustards on Monday, becoming the fourth arrival at the Stade Gaston Gerard this summer after his compatriot Bruno Ecuele Manga, Guinea Bissau’s Mama Balde and Bryan Soumare.
Ndong started his career with Cercle Mberi Sportif before joining Tunisian side CS Sfaxien in 2011, where he signed his first professional contract.
The midfielder moved to France to team up with Lorient in 2015 and made 48 league appearances, scoring two goals.
On the back of the fine performances with the Merlucciidaes, Sunderland secured his signature in 2016 and featured in 49 Premier League games for the side during his stay.
Ndong expressed his desire to part ways with the Black Cats in 2018 following their relegation to the English League One.
The midfielder subsequently failed to show up at the Stadium of Light during pre-season and also missed the start of the 2018/19 season.
On his return on September 24, he was sacked by Sunderland for breaching his contract, despite offering to take a pay cut.
The Gabon international went on to join Guingamp in January and made 11 league appearances for the Costamoricans as they were relegated to the Ligue 2.
Ndong could make his debut for his new club Dijon when they take on Nimes in a pre-season friendly game on Saturday.