The selection of the 33-year-old Akhtar came after the Pakistan Cricket Board (PCB) softened its stance on a demand for payment of a seven million rupees (90,000 dollars) fine.
The PCB said last month that Akhtar, who has not played for Pakistan this year because of injury and discipline problems, would only be allowed to play if he pays the fine.
"We have included Akhtar after clearance from the PCB and hope that he delivers the goods in the tournament," chief selector Salahuddin Ahmed said.
The four-nation event runs from October 10-13 in Toronto. Sri Lanka, hosts Canada and Zimbabwe complete the line-up.
Akhtar, who last played in the Bangalore Test against India in December, was set to return to international cricket for the Champions Trophy but the September event was postponed over security fears in Pakistan.
The maverick bowler -- known as the Rawalpindi Express for the sheer pace of his deliveries -- was in April banned for five years for publicly criticising the PCB after he was left out of a 15-man list for lucrative contracts.
A PCB appeal committee reduced the ban to 18 months but also imposed a fine in June. Akhtar then challenged the reduction and fine in Lahore High court, which suspended the ban but upheld the fine in July.
Yousuf, who was left out of the side that finished runners-up to India in last year's Twenty20 World Cup held in South Africa, failed to impress in the ongoing domestic Twenty20 event in Lahore.
But PCB chief Shafqat Naghmi said Yousuf's passport did not return from the Canadian high commission. "Otherwise he would have been in the 15-man squad," Naghmi said.
All-rounder Shahid Afridi is in the team despite poor recent batting form, while another all-rounder, Fawad Alam, also staged a comeback after being left out of the Champions Trophy squad.
The 23-year-old paceman Anwar Ali and opener Shoaib Khan, also 23, have not played for Pakistan at senior level.
Squad: Shoaib Malik (capt), Salman Butt, Shoaib Khan, Khalid Latif, Younis Khan, Misbah-ul Haq, Shahid Afridi, Kamran Akmal, Shoaib Akhtar, Sohail Tanveer, Umar Gul, Fawad Alam, Anwar Ali, Sohail Khan, Abdur Rauf