Both of them were welcomed by Punjab Congress Predeint Captain Amarinder Singh.
Kaur, a BJP legislator from Amritsar and a parliamentary secretary in the Akali-BJP government, had resigned as MLA following differences between the BJP leadership and her husband.
Hinting at Sidhu's entry to the Congress, Navjot Kaur said: "We are like one soul in two bodies. The body has to follow the soul."
Unconfirmed reports say Sidhu too would join the Congress and campaign for the party.
His wife and Pargat, a former Akali MLA, had met Amarinder last week. Sidhu is said to have met Rahul Gandhi.
(With agency inputs)