The Arsenal superstar was due to report for pre-season on Sunday.
However, he was given extended leave due to illness.
But lawyer Ruben Inostroza Povea has shared an image to his Instagram account confirming Sanchez's return to England.
The pair flew out from Sanchez's native Chile yesterday, stopping at Paris on the way.
The Independentsay he returned to the UK via France in order to renew his work permit.
Sanchez's failure to arrive on time raised suspicion among some who thought he might be going on strike.
The 28-year-old shared a picture on himself looking glum when he was supposed to be on his way back to north London.
But boss Arsene Wenger insisted Sanchez would stay following the forward's no-show.
He said: "There is no development in his future it is always the same. He is staying, of course.
"I cannot reveal what he says, I can't reveal secret conversations."
