His broadcast media career began at CKDH in Amherst, Nova Scotiain the summer after his graduation, followed by work at CKCW in Moncton, New Brunswick and at CHNS in nearby Halifax, Nova Scotia. In 1986 he joined the Canadian Broadcasting Corporation. He worked for CBC bureaus in the Maritimes and Toronto, Ontario before moving to Vancouver, where he was a network reporter and hosted the now-defunct programs Pacific Rim Report, Foreign Assignment, and Times 7 and also hosted a summer series on CBC Radio One, Feeling the Heat. From 2000 to 2007, he was the anchor of the national segment of the defunct newscast Canada Now; following that program's cancellation, he was the co-anchor of CBC News: Vancouver, CBUT's supper hour newscast, from 2007 to 2010. He returned to his former role as network reporter for The National in 2010 and from 2012-2017 he hosted CBC News Now with Ian Hanomansing, which was broadcast live from CBC Vancouver on weeknights. On August 1, 2017, he was named as one of four new co-hosts of The National, CBC's flagship news broadcast alongside Adrienne Arsenault, Rosemary Barton and Andrew Chang. In 2020, he was named the Friday and Sunday anchor of the programme. Hanomansing has developed and hosted a series of innovative live news specials including "Downtown Drugs", in November 1998, from Vancouver's Downtown Eastside during a public health emergency declared after a high number of fatal overdoses. In March 2005, "Crime on the Streets" was broadcast, in part, from Stoney Mountain Institution in Manitoba. It is believed to be the only live national news special from a Canadian federal penal institution. It won a national Justicia Award for Excellence in Legal Reporting, as well as a Jack Webster Award. Hanomansing received an honorary degree, Doctor of Lawshonoris causa, from Mount Allison University in 2003. On November 28, 2008 Hanomansing won the Gemini Award for Best News Anchor, beating Kevin Newman and Peter Mansbridge. In March 2016, he won the Canadian Screen Award for Best National News Anchor over Peter Mansbridge, Lisa LaFlamme and Heather Hiscox. Hanomansing also designed Big League Manager, an NHL-licensed board game. His game was voted a "Best Bet" by the Canadian Toy Testing Council.