According to various sources, including the BBC, the popular manager was attacked while signing autographs at the airport in the city of La Coruna in northern Spain, where Mourinho's Real Madrid played last weekend.
The ex-Chelsea coach reportedly escaped unharmed, but a team security staffer was "left with a small wound under his arm."
The incident took place last Friday, but it was only reported today, a week later, by the Cadena Sur news channel in Spain.
According to Cadena Sur, the member of the security team didn't know he had been stabbed until he was on the team bus shortly thereafter.
A Real Madrid source reportedly told Cadena Sur that the club has increased security for this weekend's match against Racing Santander.