In this paper, we propose an experimentally viable scheme to enhance the sensitivity of force detection in a hybrid optomechanical setup assisted with squeezed vacuum injection, beyond the standard quantum limit (SQL). The scheme is based on a combination of the coherent quantum noise cancellation (CQNC) strategy with a variational homodyne detection of the cavity output spectrum in which the phase of the local oscillator is optimized. In CQNC, realizing a negative-mass oscillator in the system leads to exact cancellation of the backaction noise from the mechanics due to destructive quantum interference. Squeezed vacuum injection enhances this cancellation and allows sub-SQL sensitivity to be reached in a wide frequency band and at much lower input laser powers. We show here that the adoption of variational homodyne readout enables us to enhance this noise cancellation up to 40 dB compared to the standard case of detection of the optical output phase quadrature, leading to a remarkable force sensitivity of the order of 10 −19 N/
√Hz, 2-order enhancement compared to the standard case. Moreover, we show that at nonzero cavity detuning, the signal response can be amplified at a level 3-to 5-times larger than that in the standard case without variational homodyne readout, improving the signal-to-noise-ratio (SNR).