Campbell was born in 1964; his parents are Jim and Wendy Campbell. He graduated from Wellington College and then from Victoria University with a Bachelor of Arts degree with Honours. Campbell got his first taste of broadcasting at Victoria University’s Radio Active as a student where, as “Sparky Plug”, he provided humorous “alternative rugby commentaries” during All Black games which he now describes as “unbelievably rude” and “grossly defamatory”. He then worked as a share trader, providing a share report to Radio New Zealand’s Midday Report. In 1989, Radio New Zealand (RNZ) offered him a job as a business reporter. He had no journalism training, but RNZ ran a cadetship system which provided him with the experience he needed. He read the three-minute news bulletins on the hour for RNZ, and then moved to TV3 in 1991 as a general reporter in their Wellington newsroom. He moved to their political press gallery a year later.