Congress president Amarinder said all these leaders had joined the party "unconditionally".
Congress today got a boost ahead of the Punjab Assembly elections, with some leaders from Shiromani Akali Dal (SAD), Aam Aadmi Party and BJP joining the party in the presence of Pradesh Congress Committee chief Amarinder Singh today.
Former SAD leader from Atam Nagar and councillor Kamaljit Singh Karwal, once considered close to legislator Simarjit Singh, and former AAP central executive committee member Yamini Gomar were among those pledged their allegiance to Congress.
Other AAP leaders to join Congress were L R Nayyar, former chief commissioner (Income Tax), and party observer Gagan Sahni.
Speaking on the occasion, Punjab Congress president Amarinder said all these leaders had joined the party "unconditionally".
"They had become completely disillusioned with the policies of their respective parties and the agendas of their leaders," he said.
Mr Amarinder hailed their joining as another milestone in the Congress's journey towards a "clear majority" in the upcoming Assembly polls, saying these developments highlighted the "complete wipeout" of all the other parties in the fray.
Mr Karwal, who had met Amarinder in Delhi, was associated with SAD since 2007, except for a brief period in 2014.
"The anti-people policies of the party," he said, had encouraged him to take the decision to move to the Congress.
Ms Yamini, who had openly accused Mr Kejriwal and AAP of being "anti-Dalit, anti-Sikh and anti-Punjab," said, "AAP was in a total mess, with its leadership befooling the people of Punjab with fake promises."
"AAP leadership is not even ready to blink its eyes over the issues of corruption and promotion of criminals in the party," she said.
Ms Yamini said there was hardly any AAP leader who fulfilled the party's motto of not being involved in corruption and not having criminal record.
"More than 70 per cent of the AAP volunteers, who had joined the party with an aim to see Punjab on roads of progress, are completely shattered with party leaders busy promoting their own vested interests", she said.
Many more genuine people in AAP, who were feeling suffocated there, would join Congress fold in the coming days.
Ms Yamini, who contested 2014 Lok Sabha elections on AAP ticket, said no honest person who has the interests of Punjab in his heart can remain with AAP, given the complete moral bankruptcy of its leadership.
She said the Congress could save the state and its people from doom.
Both Mr Nayyar and Mr Sahni also backed Ms Yamini, saying AAP was a party of "corrupt and greedy individuals who had no interest in the welfare of the people of Punjab."
Meanwhile, a number of the BJP leaders from Doraha, also joined Congress.
Prominent among them were Doraha BJP Mandal chief Rahul Bector, vice-president Anish Bector, secretary Varun Sharma and general secretary Anoop Bector, besides several Municipal Councillors and other BJP leaders.