After representing France U20, Knockaert was called up by France U21 for the first time and made his France U21 debut, scoring in a 2–1 win over Chile U20 on 10 September 2012.
Setelah mewakili Prancis U20, Knockaert dipanggil oleh Prancis u-21, untuk pertama kalinya dan membuat- debutnya di Prancis U21, mencetak gol di kemenangan 2-1 atas Chile U20 pada tanggal 10 September 2012.