Rashid Godil, a former lawmaker and leader of Muttahida Qaumi Movement (MQM), joined Pakistan Tehreek-i-Insaf (PTI) on Sunday.
Godil announced his decision to join the party during a meeting with PTI Chairman Imran Khan at the latter's Bani Gala residence.
Former PTI secretary general Jahangir Tareen, Mian Mahmoodur Rasheed and Zulfi Bukhari also attended the meeting.
According to an official announcement by the PTI Central Media Department, Imran Khan "warmly welcomed" Godil in the party fold.
Godil, the notification said, expressed his complete confidence in the leadership of Imran Khan and the PTI's manifesto.
On the occasion, Imran Khan issued a video message and said that the dream of making Pakistan a developed country could never be fulfilled without uplifting Karachi.
He expressed hope that the PTI would improve its performance in Karachi in the upcoming general elections, and 'predicted' that PTI would emerge as the single largest party in Karachi.
In his video message, Khan said that Godil's joining would help him bring 'real change' in Karachi. He said Godil had a good network in Karachi, which would prove beneficial for the PTI.
The reports of Godil's switching loyalties Pakistan had been in circulation in the social media for the past few weeks.
The 58-year-old politician belongs to the business community. He stepped into the political arena in 2005. The same year, with the help and support of MQM, he became Union Council Nazim. During the 2008 general election, he was elected MNA on an MQM ticket from NA-252, Karachi. He retained his NA membership from the same constituency in the 2013 general election.
In August 2015, Godil survived an assassination bid and was critically wounded after unidentified attackers opened fire at his vehicle near his residence in Karachi's Bahadurabad area. He had suffered five bullet wounds on his chest, head and arm.