During his four years at Brown University in Providence, Rhode Island, Dennis completed a Bachelor of Arts degree in economics.

From 1983 to 1987, Dennis completed his articles and was an associate lawyer with Weir & Foulds, now WeirFoulds LLP, with a focus on real estate development, litigation and dispute resolution.

In 1987, Dennis joined Blake, Cassels & Graydon, which is one of Canada's leading law firms,[1] where he worked in their real estate department.

Ashton-Royce started out as a real estate syndication company focusing on commercial, industrial and retail investment properties in the Greater Toronto Area.

Through Cale Financial Corporation, Dennis provided strategic advice and financing to entrepreneurs and the CEOs of fast growth businesses.

In 2012, Jeff Dennis became the world's only entrepreneur in residence in a law firm when he joined Fasken Martineau DuMoulin LLP in that capacity.

In 2003, Dennis, along with co-author Jana Matthews, wrote Lessons from the Edge: Survival Skills for Starting and Growing a Company (Oxford University Press).

Dennis's most popular presentations are the "Lessons from the Edge", "The Perfect Pitch", "The Canadian Financial Landscape for Startups" and "Partnerships: A Necessary Evil?".

In 2014, Jeff Dennis was named Runner up for the Starters Canada Ontario Mentor of the Year reflecting his commitment to the startup ecosystem in the Greater Toronto Area.