Mawufemor Bierko was a foreign exchange student working for the organization as a staff accountant at the time of the thefts, the Los Angeles Times reported Thursday.
Bierko, 35, pleaded guilty Wednesday to one count of grand theft embezzlement and two counts of forgery, all of them felonies, the Orange County district attorney's office said in a statement
He was sentenced to five years and four months in prison and ordered to pay restitution to the Girl Scouts of $102,479.
Prosecutors said Bierko forged 22 checks over a period of 11 months between January 2010 and February 2011 and manipulated spreadsheets to cover up the missing money.
The embezzlement was discovered when a supervisor noticed hidden columns in the spreadsheets with entries that were invisible to the naked eye.
By the time the thefts were noticed, prosecutors said Bierko had cleaned out his desk, deposited two forged checks and caught a flight back to Ghana.
He later returned to the United States and was arrested in June 2012 in Green Bay, Wis., while waiting to catch a flight back to Ghana, they said.