Terahertz (THz) metamaterial modulators offer multifaceted capabilities for various practical applications such as THz imaging, wireless communications, sensing, et cetera. However, compared to the modulation devices for other electromagnetic bands, the ubiquitous proliferation of THz applications is severely impeded by the tremendous lack of complementary metal-oxide-semiconductor (CMOS) compatible technology. Here we demonstrate a CMOS based actively tunable THz metamaterial array (C-ATTMA) with split ring resonators (SRRs). The THz metamaterial modulators can be externally controlled with an electrically-controlled dynamic. The C-ATTMA fabricated by the 180 nm CMOS technology featuring a resonant frequency of 0.30 THz was connected to the source and drain of a bottom metal-oxide-semiconductor field effect transistor (MOSFET) through the vias. By delicately controlling the MOSFET gate voltage, the equivalent circuit response of the C-ATTMA was actively engineered, enabling tailoring THz resonance frequencies. Under a gate voltage of 1.8 V, we successfully realized a 35 GHz modulation bandwidth with [[EQUATION]] phase modulation. The exhibited CMOS-compatible electrically-regulated THz metamaterials may provide enormous potentials for implementing THz wireless communications, information encryption, THz compressed sensing imaging, et cetera.