Born in Howland Street, Tottenham Court Road in Camden, London, the son of a police-magistrate, Ballantine was educated at St Paul's School, and called to the Bar in 1834.

As a young man he had a wide familiarity with dramatic and literary society, meeting many writers, including Charles Dickens, William Makepeace Thackeray and Anthony Trollope, and this background helped to obtain for him a large legal practice, particularly in criminal cases.

'[citation needed] The Law Times, in a brief notice,[1] stated that Ballantine "left behind him scarcely any lesson, even in his own poor biography, which the rising generation could profitably learn."

But in the same issue there is a full obituary with a detailed description of his life and career, ending with "[…] he had an individuality of character which gave him a position almost unique in the estimation of the public.

Barrister and politician Sir Edward Clarke wrote [2] that Ballantine spent the latter part of his life "in exile at Boulogne, only being saved from poverty by the allowance made him by his son, which was generously supplemented by six members of the Bar".

The DNB [3] reports that he left no issue, but a variety of other sources[4][5] record that he was the father of William Henry Walter Ballantine, an attorney on the South Eastern Circuit and a Member of Parliament.