He was a research professor at University of Connecticut, and was previously the head of faculty and professor at Hartford Graduate Campus of Rensselaer Polytechnic Institute in Hartford, Connecticut and prior to that, a member of the faculty at Swinburne University of Technology in Hawthorn, Victoria, Australia where he attained tenure in 1997.
Younessi was recognized for his work in the fields of defect management, software and system development processes and was an authority in object-oriented computing.
His primary interest was in systems and functional biology, particularly work that pertains to disease and development.
He also holds a master's degree in management, specializing in realistic alternative frameworks in economics and finance.
Younessi died on 23 March 2016, due to complications arising from small cell lung cancer.