The 29-year-old complained of knee trouble during last month's tour of South Africa and was sidelined after playing the first two games of the five-match one-day series.
The Pakistan Cricket Board (PCB) announced Gul would head to Australia for an operation next month.
"Gul complained of right knee pain during the South Africa tour. He was rested for imminent damage to his medial meniscus and bone of right knee. On his arrival back to Pakistan he underwent MRI scan which confirmed knee problem," a PCB release said.
Gul's initial reports were sent to Australia where a specialist advised surgery and rest and gave a timeframe of 8-12 weeks for full recovery. The PCB said they hoped the operation would go ahead in Melbourne early next month.
The bowler has taken 163 wickets in 47 Tests and 167 in 116 one-day internationals. He is also the leading wicket-taker in Twenty20 internationals with 74 in 52 matches.
Pakistan are in Group B alongside India, the West Indies and South Africa in the Champions Trophy to be played in England from June 6-23.
Defending champions Australia, Sri Lanka, England and New Zealand form Group A.
