Johnson has been a revelation for Motherwell since joining the club from Kidderminster Harriers in January 2015.
The skilful winger played a key role in helping Motherwell secure survival in the Scottish Premiership in his first six months at the club and he was a virtual ever-present last season, making 42 appearances and scoring six goals.
A number of clubs in England have been keeping tabs on Johnson after watching him in action on several occasions, but Celtic, Rangers and Hearts are all keen to keep the player in Scotland.
Rangers have held a long-term interest in Johnson and tried to sign him last summer, while Celtic and Hearts are big admirers of the attacker.
The 25-year-old was rewarded for his fine form with a new three-year deal at Fir Park last June, but Motherwell are bracing themselves for interest in their prized asset this summer.
Motherwell boss Mark McGhee recently admitted he would be amazed if no one came in for Johnson this summer telling Herald Scotland: "I have Marvin Johnson although I will be amazed if no-one takes him, but at the moment he's still here."