Henslow was educated at St. John's College, Cambridge where he graduated as 16th wrangler in 1818, the year in which Adam Sedgwick became Woodwardian Professor of Geology.
Henslow dididik di St. John's College, Cambridge dimana ia lulus sebagai wrangler ke-16 pada 1818, tahun dimana Adam Sedgwick menjadi Profesor Geologi Woodwardian.