He was the eldest son of Thomas Arnold and his wife Mary Penrose Arnold, born on 24 December 1822 at Laleham-on-Thames, Middlesex.[3] John Keble stood as godfather to Matthew.
In 1828, Thomas Arnold was appointed Headmaster of Rugby School, where the family took up residence, that year. From 1831, Arnold was tutored by his clerical uncle, John Buckland, in Laleham. In 1834, the Arnolds occupied a holiday home, Fox How, in the Lake District. There William Wordsworth was a neighbour and close friend.
In 1836, Arnold was sent to Winchester College, but in 1837 he returned to Rugby School. He moved to the sixth form in 1838 and so came under the direct tutelage of his father. He wrote verse for a family magazine, and won school prizes. His prize poem, "Alaric at Rome", was printed at Rugby.
In November 1840, aged 17, Arnold matriculated at Balliol College, Oxford, where in 1841 he won an open scholarship, graduating B.A. in 1844.[3][4] During his student years at Oxford, his friendship became stronger with Arthur Hugh Clough, a Rugby pupil who had been one of his father's favourites. He attended John Henry Newman's sermons at the University Church of St Mary the Virgin but did not join the Oxford Movement. After his father's death in 1842, Fox How became the family's permanent residence. His poem Cromwell won the 1843 Newdigate prize.[5] He graduated in the following year with second class honours in Literae Humaniores.
In 1845, after a short interlude of teaching at Rugby, Arnold was elected Fellow of Oriel College, Oxford. In 1847, he became Private Secretary to Lord Lansdowne, Lord President of the Council. In 1849, he published his first book of poetry, The Strayed Reveller. In 1850 Wordsworth died; Arnold published his "Memorial Verses" on the older poet in Fraser's Magazine.
