During World War II he served as an aircraft mechanic in the United States Air Force, including an active service deployment to England in 1944–45.

Dundee acted as cornerman for Leonard in many of his biggest fights, including those with Wilfred Benítez, Roberto Durán, Thomas Hearns, and Marvin Hagler.

In Leonard's first bout with Hearns, Dundee, thinking that his protégé was behind on the scorecards, quipped the now famous words, "You're blowing it, son!

During the first Joe Frazier vs. George Foreman bout in Kingston, Jamaica, on January 22, 1973, he sat near Howard Cosell, who was recording a call for ABC for a tape delay re-broadcast.

The fight was finally stopped after Frazier was knocked down for the sixth time, with Foreman winning the bout—and the lineal World Heavyweight Championship—by technical knockout.

In addition, Dundee also trained world champions Luis Rodriguez, Willie Pastrano, Ralph Dupas, José Nápoles, Pinklon Thomas, Trevor Berbick, Jimmy Ellis, Wilfredo Gómez, Michael Nunn and Sugar Ramos, as well as other boxers including Bill Bossio, David Estrada, Douglas Vaillant, Jimmy Lange, Tom Zbikowski, Troy Darrell, Adilson Rodrigues, James Tillis,Pat O'Connor and Sean Mannion.

To that end, Dundee traveled to Australia to work with the Oscar-winning actor and appeared in the film as "Angelo" the corner man.

[9][10] A funeral was held on 10 February 2012 at the Countryside Christian Center in Clearwater, Florida, attended by a crowd of several hundred mourners, among them Muhammad Ali.