This study proposed an enhanced two-port dual-band textile Multiple-Input Multiple-Output (MIMO) antenna integrated with a metamaterial unit cell of symmetric decagonal C-shaped Complementary Split-Ring Resonator (CSRR) structure in terms of gain. The proposed MIMO antenna achieves an impedance bandwidth of 6.3% and a maximum up to 18.2% for lower and upper bands, respectively, at port 1. Mutual Coupling (MC) of less than -20 dB for both ports is obtained. The proposed antenna offers high realized gain of 5.6 dBi and 8 dBi at 2.45 GHz and 3.5 GHz, respectively, compared to existing dual-band MIMO textile antenna. Good diversity characteristics in respect of Envelope Correlation Coefficient (ECC) less than 0.001, and Diversity Gain (DG) of about 10 dB are achieved.