[en] We report the results of a search for the neutrinoless double-β decay (0νββ) of ¹⁰⁰Mo, using the NEMO-3 detector to reconstruct the full topology of the final state events. With an exposure of 34.7 kg.y, no evidence for the 0νββ signal has been found, yielding a limit for the light Majorana neutrino mass mechanism of T_1/2 (0νββ≥ 1.1 * 10²⁴ years (90% C.L.) once both statistical and systematic uncertainties are taken into account. Depending on the nuclear matrix elements this corresponds to an upper limit on the Majorana effective neutrino mass of (m_ν ≤ 0.3-0.9 eV (90% C.L.). Constraints on other lepton number violating mechanisms of 0νββ decays are also given. Searching for high-energy double electron events in all suitable sources of the detector, no event in the energy region [3.2-10] MeV is observed for an exposure of 47 kg.y. (authors)