Low‐temperature photoluminescence (PL) related to Co deep impurities in In1−xGaxP (0.74≤x≤1) and GaAs1−xPx(0.65≤x≤1) alloys has been studied. Broad PL bands with some structures have been observed in the 2.3‐&mgr;m region for both the alloys. The results of time‐resolved PL measurements have shown that the PL bands are due to the intracenter transitions4T2(4F)→4A2(4F) in a substitutional Co2+ion in the zinc‐blende lattices. These Co‐related PL spectra have been analyzed in terms of the local atomic arrangements around the Co luminescent center. As a result, it has been found that these Co‐related PL spectra in InGaP and GaAsP alloys are composed of several bands closely related to the local arrangement of atoms around the Co center.