The 33-year-old was absent from the Australian Open after being provisionally suspended last month for testing positive for anabolic steriod Boldenone in October 2019.
However, Wimbledon and US Open champion Farah is free to compete again after he successfully argued his positive test came as a result of eating contaminated meat in his homeland.
In a statement, the ITF said: "Mr Farah's account of how the Boldenone entered his system was accepted and it was determined that he bears no fault or negligence for the violation.
"Therefore, the player's provisional suspension is lifted with immediate effect, and he will not serve any period of ineligibility for his violation.
"For the avoidance of doubt, Mr Farah is eligible to resume competition immediately."
The Colombian thanked his family, sponsors and fans who "supported me during this trying time to prove my innocence".
His legal counsel, Maurice M Suh, welcomed the finding on his client's behalf.
"We are pleased that the ITF has found in favour of Mr Farah and has fairly applied the tennis anti-doping rules," he said in a statement.
"Mr Farah is a champion and deserves to return to competition and the sport he loves."
Additional reporting from the Press Association.