Greenwood, who has been capped for England, was arrested last January when allegations emerged of him accusing him of rape and assault.
He was suspended by Manchester United at the time on full pay, while Greater Manchester Police (GMP) investigated the allegations.
He was rearrested several days later following allegations that he had made threats to kill him.
In October last year, following an allegation that he had breached his bail conditions, Greenwood was charged with one count of attempted rape, one count of controlling and coercive behaviour, and one count of assault occasioning actual bodily harm.
The GMP, which conducted the lengthy investigation into the allegations, said it understood why the decision to drop the case had been taken, adding that it was not something that had been done lightly.
Chief Supt Michaela Kerr, GMP’s head of public protection, said: “I would, however, like to use this opportunity to reiterate GMP’s commitment to investigating allegations of violence against women and girls and supporting those affected, regardless of their circumstances, throughout what can be a hard and upsetting time for them.
“An ever increasing number of officers are receiving specialist training and the force is more consistently utilizing tools, available via the criminal justice system, to keep people safe and care for victims. If you feel you are or might be a victim, please don’t let this case put you off asking for help.”
Despite criminal proceedings now being at an end, the footballer’s future with Manchester United remains uncertain.
It is understood that he will not return to training or playing for the time being, while the club carries out an internal review of his alleged conduct.
A spokesman said: “Manchester United notes the decision of the Crown Prosecution Service that all charges against Mason Greenwood have been dropped.
“The club will now conduct its own process before deciding next steps. We will not make any further comment until that process is complete.”
It is understood the club will carry out an internal investigation.