Before working with a rock band, he was a jouster at a Medieval Times Dinner Theater. He was introduced to the band Symphony X by former singer Rod Tyler. Allen has been the lead singer of Symphony X since 1995, releasing seven studio albums and one live album with the band. His first solo album, Atomic Soul, was released April 25, 2005. As well as singing he also plays the bass when performing songs from Atomic Soul live. He is referred to in various circles as "Sir Russell Allen", and he is credited as such on Arjen Lucassen'sStar One albums, because of a joke that Arjen made knowing Allen's former "job" as a jouster.
In addition to being Symphony X vocalist, he is also currently working in another band with guitarist Mike Orlando called Adrenaline Mob. The EP, Adrenaline Mob, was released in August 2011. The first full length album Omertà was released in March 2012 and a new album called Men of Honor will be released in 2014.
In 2014 a new project was announced, featuring Russell Allen with bassist Mat Sinner and other members of the German band Primal Fear, called Level 10, with an album release slated for January, 2015. The release date and the name of the album were revealed in November, 2013: it would be titled as "Chapter One", to be released on January 23rd, 2015 in Europe and on January 27th, 2014 in North America via Frontiers Music srl. 
Multi-instrumentalist, singer and composer Arjen Lucassen has said the following regarding Russell Allen:
Russell has a very powerful and versatile voice, and on top of that he is a great musician and performer. Russell was one of the few singers with whom I didn’t need to be present during recording, but when on the phone he let me hear the parts he had sung, my eyes filled with tears. Russell thought I was joking, but I was truly moved! At the moment Russell is one of the best singers in the world. And he proved that during the Star One tour.