A wideband and high-isolation mobile phone antenna pair with low envelope correlation coefficient (ECC) for fifth-generation (5G) smartphone applications based on four orthogonal modes is proposed in this communication. According to the characteristic mode analysis, except for the original two resonant modes, the other two resonant modes are introduced by arranging a metallic strip at the top of the vertical bezel. With the help of dual-mode excitation and orthogonal property, wideband and high-isolation merits are achieved for the shared radiator antenna pair. Finally, four antenna modules are deployed along the long edge of the system circuit board to form an 8 × 8 multiple-input multiple-output (MIMO) system. The measured results prove that the impedance matching bandwidth of the fabricated prototype ranges from 3.3 to 5 GHz while the isolation level is higher than 17.5 dB. The antenna efficiencies are higher than 45% and 48% for the two different antenna elements. Guaranteed by the orthogonal relationship between different characteristic modes, the extremely low ECC (<0.04) is achieved.