Amir, 22, was jailed for six months and banned for his part in a spot-fixing scam during Pakistan's tour of England in 2010.
"The apex cricket body's Anti-Corruption and Security Unit (ACSU) chairman Sir Ronnie Flanagan, with the prior approval of the ICC Board and the Pakistan Cricket Board, has exercised his discretion to allow Mohammad Amir to return to domestic cricket played under the auspices of the Pakistan Cricket Board with immediate effect," the ICC said in a statement following the conclusion of its two-day Board meetings here.
Amir, then 17, delivered pre-arranged no balls at Lord's in a plot that also led to the banning of Mohammad Asif and then captain Salman Butt.
The ICC further said: "The ACSU Chairman had exercised the powers vested in him under Article 6.8 of the ICC Anti-Corruption Code after he was satisfied that Amir had cooperated with the ACSU by fully disclosing his part in the matters that led to his disqualification, admitting his guilt, showing remorse and cooperating with the Unit's ongoing investigations and by recording messages for the ACSU education sessions."