Purposes The main purpose of this study is to investigate whether there is a difference in phoneme recognition and school-age language skills in children with bilateral and unilateral cochlear implants (CI). The second aim of the study is to examine language-based skills in bilateral cochlear implanted children with the first implant, second implant and in the bilateral listening situations. Method 60 to 108-month-old children with similar demographic and audiological features were included. Of the 64 participants in total, 30 are bilateral cochlear implant users and 34 of them use unilateral cochlear implants. Turkish version of "Test of Language Development-Primary: Fourth edition (TOLD-P:4)" and "Phoneme Recognition Test (PRT)" were implemented for the evaluation of the language sub-components skills and auditory perception. In addition, the PRT test audio file was presented directly to the implant with connection cables via the fitting program methodologically. Results Children with bilateral cochlear implants were more successful in all language-based skills than children with unilateral cochlear implants (p < 0.05). In the PRT test, the most successful scores were obtained in the bilateral listening conditions, the second with the experienced implant side, and the most unsuccessful scores in the listening conditions with second implant. Conclusion Bilateral cochlear implants are very useful in terms of language-based skills in children with severe/profound hearing loss. This can positively affect even the future academic and social skills of children.