A microelectromechanical detection structure for a MEMS resonant biaxial accelerometer is provided with: an inertial mass, anchored to a substrate by elastic elements to be suspended above the substrate. The elastic elements enabling inertial movements of the inertial mass along a first axis of detection and a second axis of detection that belong to a plane of main extension of said inertial mass, in response to respective linear external accelerations. At least one first resonant element and one second resonant element have a respective longitudinal extension, respectively along the first axis of detection and the second axis of detection, and are mechanically coupled to the inertial mass through a respective one of the elastic elements to undergo a respective axial stress when the inertial mass moves respectively along the first axis of detection and the second axis of detection.