Being able to tune the anisotropic interband transitions in phosphorene at finite temperature offers an enormous amount of possibilities in finding new insights in the optoelectronic community. To contribute to this goal we propose a Zeeman spin-splitting field aiming at absorbing various frequencies of the incident light. Employing the tight-binding Hamiltonian to describe the carrier dynamics and the Kubo formalism to formulate the orientation-dependent interband optical conductivity (IOC) and optical activity of phosphorene we investigate the absorption and scattering mechanisms in phosphorene depending on the Zeeman field strength and optical energy parameters. The optical activity features are characterized by exploring the eccentricity and shift phase of reflected and transmitted electromagnetic waves of the incident light. Different electronic phases in the absence and presence of Zeeman field ultimate different types of interband transitions of which in all cases the IOC along the armchair direction is larger than the zigzag one. However, we observed an irregular (regular) process for IOC with the Zeeman field along the armchair (zigzag) direction, resulting in irregular (regular) absorption and scattering mechanisms. Additionally, a little to no effects for temperature-dependent IOC are provided with the Zeeman field in undoped phosphorene. Further, almost linearly and elliptically polarizations are reported for the transmitted and reflected waves, respectively, indicating that the phosphorene is almost transparent. The emergence of Zeeman spin-splitting effects in optoelectronic properties of phosphorene is pleasant to make it a great potential candidate for logic applications.