"I have tested positive for #Covid with mild symptoms. Have isolated myself and request all those who came in contact with me to get themselves tested," he wrote in his tweet.
The 79-year-old leader had recently formed the Punjab Lok Congress.
Singh's wife and Congress MP from Patiala, Preneet Kaur had also tested positive for the virus a few days ago.
Meanwhile, the former Chief Minister Amarinder Singh's newly launched political outfit Punjab Lok Congress said it has got a "hockey stick with ball" as the party symbol for the February 14 state assembly polls.
"Happy to inform that Punjab Lok Congress has received its Party Symbol- Hockey Stick with Ball. #Bas Hun Goal Krna Baki (Making goals only left now)," the Punjab Lok Congress said in a tweet earlier.
Voting in Punjab will be held on February 14 and the counting will take place on March 10.