The former insurance underwriter pleaded guilty last September to 27 felony counts of indecent exposure.
Fenn was arrested in February 2008, after he exposed himself to a woman who lived on the first floor of an apartment on Heritage Way in Tustin.
The woman screamed and Fenn was spotted by a couple walking nearby in a parking lot. The man chased Fenn, who threw a brick at him and tried to run from the scene.
Tustin Police arrived and arrested Fenn.
An investigation revealed that between July 2005 and the arrest date, Fenn exposed himself to nearly 100 women.
He was linked to incidents in eight communities in south Orange County.
Fenn is married and the father of four children.
Some of the victims attended Friday's sentencing. One woman, who was a victim twice, told the court she has nightmares and wakes up crying because of Fenn.