Butt, 27, was jailed for 30 months last November on charges of accepting corrupt payments during the Lord’s Test against England in August 2010, AFP reported.
Butt, team mates Mohammad Asif and Mohammad Aimr, and agent Mazhar Majeed were accused of contriving deliberate no-balls in return for money.
Aamer was released in February after serving half his six-month sentence while Asif, jailed for 12 months, was freed in May.
“We expect him to be released tonight,” Zulfiqar told Geo News.
“My son’s good behaviour has led to the decision and he will be in Pakistan in the next three to four days,” he added.
The three players were banned for at least five years by the International Cricket Council (ICC), which has ordered the Pakistan Cricket Board to rehabilitate the former stars.
The trio has a right to appeal the ICC ban in the Court of Arbitration for Sports in Switzerland.
Amir, who pleaded guilty during the trial, has decided not to appeal but Asif and Butt have hinted that they will challenge the punishment.