A system and method are provided for calibrating orthogonal polarity in a multichannel optical transport network (OTN) receiver. The method accepts a composite signal and separates the polarization of the signal into a pair of 2.sup.n-phase shift keying (2.sup.n-PSK) modulated input signals via Ix and Qx optical signal paths, where n.gtoreq.1. Likewise, a pair of 2.sup.p-PSK modulated input signals are accepted via Iy and Qy optical signal paths where p.gtoreq.1. Polarization-adjusted I'x, Q'x, I'y, and Q'y signals are generated. An average magnitude is compared to either 2.times.the absolute magnitude of (I'x and Q'x), or 2.times.the absolute magnitude of (I'y and Q'y). The average magnitude value can be used that is either 2.times.(a predetermined peak signal amplitude), or the sum of the absolute magnitudes of (I'x and Q'x) and (I'y and Q'y). The polarization-adjusted I'x, Q'x, I'y, and Q'y signals are modified until the magnitude comparison is about zero.