Citing commissioner Keith Brown had until today to make a decision but the New Zealander elected not to take action against the England co-captain.
If Brown had decided the shuddering hit was worthy of a red card, it would have triggered a citing that could have prevented Farrell playing in England's highly anticipated match against the world champions.
The clock had ticked past the 80-minute mark at Twickenham with England desperately trying to keep the Springboks at bay when Farrell smashed into replacement Andre Esterhuizen, knocking him back and dislodging the ball.
England kicked it dead but instead of blowing for time, Australian referee Angus Gardner called for a TMO review, with a potential match-winning penalty in easy range for Springbok flyhalf Handre Pollard.
After looking at the replay, officials ruled that Farrell had made enough of an effort to wrap an arm round his opponent to make the tackle legal - leaving the England No.10 punching the air in delight.
"As soon as anyone goes to the big screen you are (nervous)," Farrell told reporters.
"It was a pretty big collision. He ran hard, it's hard to get your arms around when you're both hitting each other at that much force. I tried to and thankfully it went our way.
"I didn't feel lucky, my intent was to wrap my arm. He had a 30m run up at me so it was tough, we both popped up off each other and it is difficult to keep that under control."
Farrell was yellow carded for a similar hit late in the defeat by Australia that ended England's World Cup hopes in 2015.
The hit was described as a "good solid tackle" by England coach Eddie Jones but appeared to divide opinion in the rugby world, and not just on nationality lines.
Former Ireland captain Brian O'Driscoll said the referee got the decision "spot on" while former Australia lock Justin Harrison said "just because you don't wrap doesn't mean it's a shoulder charge, when laws of physics mean it's a bounce effect."
However, former Ireland back Luke Fitzgerald, who was forced to retire at 28 with a neck injury, said that under the new interpretation of the tackle law it should have been a "minimum of a penalty...shocking adjudicating" while Sunday Times journalist Stephen Jones described the decision as ludicrous.
South Africa coach Rassie Erasmus opted to go down the sarcasm route when asked for his opinion.
"It was a good tackle, well done, because I haven't seen Andre Esterhuizen being tackled like that in a while," he said. "It's obviously something that's really effective. We should look on it and execute it like that."
Meanwhile former Hurricanes skipper Brad Shields remains on track to play the All Blacks, he's been retained in England's extended squad for the Twickenham game.