Centromeres are defined epigenetically by nucleosomes containing the histone H3 variant CENP‐A, upon which the constitutive centromere‐associated network of proteins (CCAN) is built. CENP‐C is considered to be a central organizer of the CCAN. We provide new molecular insights into the structure of human CENP‐A nucleosomes, in isolation and in complex with the CENP‐C central region (CENP‐CCR), the main CENP‐A binding module of human CENP‐C. We establish that the short αN helix of CENP‐A promotes DNA flexibility at the nucleosome ends, independently of the sequence it wraps. Furthermore, we show that, in vitro, two regions of human CENP‐C (CENP‐CCR and CENP‐Cmotif) both bind exclusively to the CENP‐A nucleosome. We find CENP‐CCR to bind with high affinity due to an extended hydrophobic area made up of CENP‐AV532 and CENP‐AV533. Importantly, we identify two key conformational changes within the CENP‐A nucleosome upon CENP‐C binding. First, the loose DNA wrapping of CENP‐A nucleosomes is further exacerbated, through destabilization of the H2A C‐terminal tail. Second, CENP‐CCR rigidifies the N‐terminal tail of H4 in the conformation favoring H4K20 monomethylation, essential for a functional centromere. Synopsis CENP‐A nucleosomes have a short αN helix incompatible with complete DNA wrapping, independent of DNA sequence. CENP‐C binds exclusively to CENP‐A nucleosomes and induces conformational changes that further differentiate CENP‐A‐containing from canonical nucleosomes. CENP‐C binds CENP‐A nucleosomes specifically. DNA ends of the CENP‐A nucleosome are further unwrapped in the CENP‐A/CENP‐C complex, due to flexible H2A C‐terminal tails. The N‐terminal tail of H4 adopts a conformation favored for centromere specific H4K20 monomethylation when CENP‐C is bound. CENP‐A nucleosomes have a short αN helix incompatible with complete DNA wrapping, independent of DNA sequence. CENP‐C binds exclusively to CENP‐A nucleosomes and induces conformational changes that further differentiate CENP‐A‐containing from canonical nucleosomes.