In this paper, we obtain an accurate estimation of the rupture velocity of the 6 April 2009 Mw 6.3 L'Aquila earthquake (Central Apennines) by analyzing its apparent source time functions (ASTFs). These ASTFs have been extracted by deconvolving an empirical Green's function (EGF) at seismic stations located 200-800 km from the earthquake. From the study of duration, shape, and directivity of ASTFs at numerous and well‐distributed stations, we show that the area between the two main slip patches of the earthquake ruptured at a relatively slow velocity (1.6 km/s). We next validate simultaneously the ASTFs and the slip model independently obtained through the joint inversion of strong‐motion, broadband teleseismic, Global Positioning System, and Interferometric Synthetic Aperture Radar data. The good agreement in shape and duration between the observed and theoretical ASTFs is an indication for the reliability of the inferred source model and for the robustness of the rupture velocity estimations of this study.