The 20-year-old has worked his way up through the ranks at the Banks's Stadium and admitted he always saw his future with the Saddlers.
Sansara told the club's official website: "I think there were a few clubs interested but there were no concrete offers on the table and I was always going to sign for Walsall.
"I am a homegrown lad, born and bred in Walsall, and my family and neighbours are all fans.
"I also feel this club has done a lot for me. It was the club that spotted me and has given me my chance, and now I would like to give something back.
"I felt a sense of loyalty and I feel the best way to repay the club is to give it my best shot and become a good professional."