He served as the head football coach at Colorado College (1904), South Dakota State College of Agricultural and Mechanic Arts (1906–1907), Marquette University (1908–1911), the University of Wisconsin–Madison (1912–1915), the University of Texas at Austin (1917–1919), and the University of Kentucky (1920–1922), compiling a career college football record of 86–39–10.

Juneau was also the head basketball coach at South Dakota State for two seasons from 1905 to 1907, tallying a mark of 7–5.

Juneau was the grandnephew of Solomon Juneau (1793–1856), a fur trader, land speculator, and politician who helped found the city of Milwaukee, Wisconsin.

Juneau retired from coaching 1923 and entered the real estate business.

He died on October 9, 1949, at the age of 70 in Milwaukee, Wisconsin.