Cantilever panel support apparatus, comprising - a longitudinal body made from a metal profile, to be fixed to a bearing structure, defining a laterally-open longitudinal seat, into which an end of the panel to be supported is adapted to be inserted, said longitudinal seat being delimited by a sidewall to be fixed to the bearing structure, a base extending in a cantilevered fashion with respect to said sidewall, and a ceiling which also extends in a cantilevered fashion from said side, placed above said base, wherein said base protrudes from said sidewall further with respect to said ceiling, there being defined a space, above said base, free from said ceiling, to facilitate maneuvers to insert the panel into the seat, - a first contact zone with the upper face of the panel, provided on said ceiling, - a second contact zone with the lower face of the panel, provided on said base, - a device locking the panel comprising at least one pressing element adapted to press, when the panel is put into place, against the lower face of the panel, so that the panel is pushed towards said ceiling; said pressing element being a cam body housed in a corresponding niche formed on said base and open onto said seat, said cam body being rotatable so as to take on at least two positions, a first position in which it does not interfere with the panel, and a second position in which one of its parts is in contact with said panel, pushing it towards said ceiling; said cam body can swivel on an axis parallel to the direction in which the longitudinal body extends; wherein said niche is formed on said base in a position comprised between said sidewall and said second contact zone, when put into place, the panel supported by said apparatus having its center of gravity external to said longitudinal body and having one end in said seat, said panel resting in a cantilevered fashion with one face on said second contact zone, and striking with the opposing face against said first contact zone, said first contact zone being adapted to act as opposition element to the rotation of the panel around said second contact zone. - a longitudinal body made from a metal profile, to be fixed to a bearing structure, defining a laterally-open longitudinal seat, into which an end of the panel to be supported is adapted to be inserted, said longitudinal seat being delimited by a sidewall to be fixed to the bearing structure, a base extending in a cantilevered fashion with respect to said sidewall, and a ceiling which also extends in a cantilevered fashion from said side, placed above said base, wherein said base protrudes from said sidewall further with respect to said ceiling, there being defined a space, above said base, free from said ceiling, to facilitate maneuvers to insert the panel into the seat, - a first contact zone with the upper face of the panel, provided on said ceiling, - a second contact zone with the lower face of the panel, provided on said base, - a device locking the panel comprising at least one pressing element adapted to press, when the panel is put into place, against the lower face of the panel, so that the panel is pushed towards said ceiling; said pressing element being a cam body housed in a corresponding niche formed on said base and open onto said seat, said cam body being rotatable so as to take on at least two positions, a first position in which it does not interfere with the panel, and a second position in which one of its parts is in contact with said panel, pushing it towards said ceiling; said cam body can swivel on an axis parallel to the direction in which the longitudinal body extends; wherein said niche is formed on said base in a position comprised between said sidewall and said second contact zone,