This paper presents a compact and wideband multiple-input-multiple-output (MIMO) antenna array for unmanned aerial vehicles (UAV) applications. The contribution of this work lies in its size reduction based on the use of dual polarized MIMO elements and wideband operation. Here, the MIMO element is a combination of a dual-polarized crossed patch combined and four parasitic elements. Then, two MIMO elements are positioned at minimal distance to construct a 4-port MIMO array. With the aid of shorting pins, high isolation between the MIMO elements can be obtained. The simulated data shows that the proposed 4-port MIMO antenna with compact dimensions of \(0.81 \, \lambda \times 0.40 \, \lambda \times 0.02 \, \lambda \) can achieve an operating bandwidth of 8.9% (4.3–4.7 GHz) with isolation of better than 20 dB.