Sanders made the announcement in a call with his campaign staff, his campaign said, CNN reported.
Sanders announced he was dropping out of the race in an email to supporters, vowing that while "the campaign ends, the struggle continues."
Wisconsin primary on Tuesday might have contributed to the senator's decision to drop out.
President Donald Trump also commented on Sanders exit and blamed Senator Elizabeth Warren for diverting a hefty chunk of votes.
"Bernie Sanders is OUT! Thank you to Elizabeth Warren. If not for her, Bernie would have won almost every state on Super Tuesday! This ended just like the Democrats & the DNC wanted, same as the Crooked Hillary fiasco. The Bernie people should come to the Republican Party, TRADE!," Trump tweeted.
Sanders took to Periscope to address his supporters after announcing his departure from the race, declaring that "our movement has won the ideological struggle" because progressive ideas like Medicare for All had gained wider acceptance.
The decision to drop out "has been very difficult and painful," Sanders said.
( With inputs from ANI )