Fordham began his career on Sydney's 2UE radio station, for which he won a Walkley Award for his coverage of the 1997 Thredbo landslide. In 1998, Fordham moved to television and joined Sky News Australia as a reporter and presenter.
After less than a year at Sky News, Fordham joined the Nine Network, working on tabloid current affair and news programs including 60 Minutes, A Current Affair, Nine News and Today.
Fordham filled in for Stuart Bocking on 2UE Nights in the 2008/09 summer period and also filled in for Ray Hadley on 2GB in the 2009/10 summer period.
In 2010, Ben joined Nine News and Today as a reporter, he also covered the 2010 federal election. In January 2011, Fordham became the Today sports presenter replacing Cameron Williams. Ben also joined 2GB in January 2011 replacing Jason Morrison to present 'Sydney Live'.
In March 2014, Fordham announced that he would be leaving Today at the end of the year to concentrate on his radio career.
In 2016, he was announced as co-host of Australian Ninja Warrior alongside Rebecca Maddern on the Nine Network.
When Fordham was seven years of age, he was diagnosed with epilepsy after suffering a seizure. He did work experience at a radio station as a teenager while a student at Saint Ignatius' College, Riverview, a Catholic college in Lane Cove.
He is managed by The Fordham Company which is run by his father, John.
In October 2011, Fordham married Seven News presenter Jodie Speers. In August 2014, Fordham announced on Today that his wife was pregnant with their first child: their son Freddy was born on 5 December 2014.
In April 2016, Fordham announced on radio that Speers was pregnant with their second child. She gave birth to daughter Pearl in October 2016.
On 26 February 2009 Fordham was charged with concealing a serious crime and breaching the Listening Devices Act. The Nine Network and A Current Affair's producer Andrew Byrne were also charged.
On 20 July 2010 NSW Supreme Court judge Elizabeth Fullerton called Fordham's attitude "disrespectful" when he failed to appear in court to hear her judgment on the charges of breaching the Listening Devices Act. Justice Fullerton found him guilty of one of four charges against him, that he knowingly recorded a conversation on 28 May 2008. Byrne was convicted of four charges of breaching the act.
The conversation was aired on ACA in May 2008, claiming to show former Waverley mayor James Markham ordering a fatal hit on a male escort. Although found guilty, Fordham and Byrne each escaped conviction, with Justice Fullerton saying it was "an appalling lack of judgment by two senior journalists who are otherwise held in esteem by their colleagues".