Born in Clifton, Bristol, England, he was the son of Dr. Thomas Beddoes, a friend of Samuel Taylor Coleridge, and Anna, sister of Maria Edgeworth. He was educated at Charterhouse and Pembroke College, Oxford. He published in 1821 The Improvisatore, which he afterwards endeavoured to suppress. His next venture was The Bride's Tragedy (1822), a blank verse drama that was published and well reviewed, and won for him the friendship of Barry Cornwall.

Beddoes' work shows a constant preoccupation with death. In 1824, he went to Göttingen to study medicine, motivated by his hope of discovering physical evidence of a human spirit which survives the death of the body. He was expelled, and then went to Würzburg to complete his training. At this period, he became involved with radical politics; this got him into trouble. He was deported from Bavaria in 1833, and had to leave Zürich, where he had settled, in 1840.

He continued to write, but published nothing.

He led an itinerant life after leaving Switzerland, returning to England only in 1846, before going back to Germany. He became increasingly disturbed, and committed suicide by poison at Basel, in 1849, at the age of 46. For some time before his death, he had been engaged on a drama, Death's Jest Book, which was published in 1850 with a memoir by his friend, T. F. Kelsall. His Collected Poems were published in 1851.