In this work, doping with TMXn (TM  = Mn and Fe; X  = N and P, n  = 3 and 6) clusters is proposed to modify the electronic and magnetic properties of PtSe2 monolayer. Pristine PtSe2 monolayer is a non-magnetic two-dimensional (2D) semiconductor material with indirect band gap of 1.40(2.01) eV obtained from PBE(HSE06)-based calculations. PtSe3-type multivacancies lead to the monolayer magnetization with total magnetic moment of 0.54 𝜇𝐵, where Pt and Se atoms around defect sites produce mainly the system magnetism. In contrast, no magnetism is induced by PtSe6-type multivacancies. The substitutional incorporation of TMXn clusters magnetizes significantly PtSe2 monolayer, where both TM and X atoms originate mainly the magnetic properties. Depending on the spin orientation in the clusters, total magnetic moments between 0.00 and 8.00 𝜇𝐵 are obtained. All the doped DTMX𝑛 systems exhibit strong spin polarization around the Fermi level, which is derived mainly from the outermost TM-3𝑑, N-2𝑝, and P-3𝑝 orbitals. Consequently, either half-metallicity or magnetic semiconductor behavior can be induced, depending on the nature of TMXn cluster. Further, the Bader analysis indicates that TMNn clusters act as charge gainers due to the more electronegative nature of N atoms in comparison with Se atoms, meanwhile TMPn clusters transfer charge to the host PtSe2 monolayer. Our study may introduce the cluster doping in PtSe2 monolayer as efficient method to create new highly spin-polarized 2D materials towards spintronic applications.