Abstract The equilibrium geometries, and electronic and magnetic properties of phosphorus, cobalt‐phosphorus, and nickel‐phosphorus ( P n+1 , CoP n , and NiP n , n = 1–24) clusters have been investigated by using first principle calculations. The doping with cobalt or nickel atom favors the endohedral structures in which the metal atom is encapsulated inside the phosphorus framework, while geometrical structures are metal‐dependent. The growth pattern behaviors and stabilities are examined from the binding energies, the second‐order energy differences, and the HOMO–LUMO gaps. The doping with Co or Ni atom contributes to strengthening the stability of the phosphorus frame with a marked improvement in the case of Ni atom. The total spin magnetic moment is enhanced with doping with Co atom. In contrast, the magnetic moment is quenched in the case of NiP n . Vertical electron affinities and ionization potentials are also reported and discussed.