Exemplary embodiments are provided of omnidirectional MIMO antennas with polarization diversity. In one exemplary embodiment, an omnidirectional MIMO antenna generally includes an array of radiating antenna elements having a linear horizontal polarization and radiating omnidirectionally in azimuth. The antenna also includes at least one radiating antenna element having a linear vertical polarization and radiating omnidirectionally in azimuth. The vertically polarized radiating antenna is spaced-apart from the array. The antenna is operable for producing omnidirectional, vertically polarized coverage for at least one port, as well as omnidirectional, horizontally polarized coverage for at least one other port.