This article presents a compact flexible four-element multiple input multiple output (MIMO) antenna for Sub-6 GHz wearable applications. A wideband monopole antenna with a modified edge truncated radiator and a lowered ground plane is replicated to form a four-element antenna. The proposed antenna is fabricated on a flexible polyethylene terephthalate (PET) substrate and holds an overall dimension of 65×56×0.25 mm3. The antenna has a measured bandwidth of 3.55-5.3 GHz with a peak gain of 4.9 dBi. A novel hybrid decoupling structure with a neutralization line in the radiator and a unique defective ground structure (DGS) suppresses the coupling current and provides isolation better than 24 dB throughout the bandwidth. The antenna design evolution is explained using characteristics mode analysis (CMA). The MIMO diversity performance is relatively good with MIMO diversity metrics showing envelope correlation coefficient (ECC) < 0.001, diversity gain > 9.99, total active reflection coefficient (TARC) < -10dB, channel capacity loss (CCL) < 0.3 bps/Hz and multiplexing efficiency (ME) < -0.5. Specific absorption rate (SAR) analysis of the antenna is performed to check the antenna’s suitability in wearable applications and the proposed antenna exhibits 0.745W/kg and 0.326W/kg for 1g and 10g of tissue respectively which is much less than the permissible international standards.