Machine and method for machining large crankshafts, which allows simple and reliable synchronization of the rotation of said crankshafts (14) at all points, where said machine has a machining tool (1) configured to move along at least one guide (2) between a first end supporting element (3) and a second end supporting element (4), comprising a first electronic angular position sensor (6) situated on a first rotation shaft (7) of said first end supporting element (3), also comprising a second electronic angular position sensor (8) located on a second rotation shaft (9) of said second end supporting element (4), so that the rotational movement of said first end supporting element (3) is electronically synchronized with the rotational movement of said second end supporting element (4) at all times during the machining of the crankshaft (14).