Lieutenant Garrett Kasper is a native of Chicago, Illinois, but considers Lisle, Illinois, his hometown. He graduated from Benet Academy in 1992, and attended Marquette University in Milwaukee, Wisconsin. He graduated with a Bachelor of Arts degree in Public Relations in 1996, and received his commission through Marquette University's Naval Reserve Officer Training Corp (NJROTC) program.

After graduating from Surface Warfare Officer School in Newport, Rhode Island, in 1997, Garrett reported to the Aegis guided-missile cruiser, USS Monterey (CG 61), home-ported in Norfolk, Virginia. He served as the ship's gunnery and ordnance officer, administrative officer and public affairs officer. Garrett also qualified as an officer of the deck underway and completed a Mediterranean deployment in 1998.

In 1999, Garrett reported as the Deputy Director of the Navy Public Affairs Center in Norfolk and deployed to the Mediterranean region to support Operation Allied Force. Upon his return to Norfolk, he served as the Deputy Director for the Fleet Hometown News Center and was officially designated as a Navy Public Affairs Officer in June 2000.

Following his graduation from the Defense Information School in Fort Meade, Maryland, Garrett reported as the Public Affairs Officer aboard USS Dwight D. Eisenhower (CVN 69) in October 2000. During that tour, he managed the ship's television news station, edited the daily newspaper and publicized numerous special events, such as the Presidential memorial service for USS Cole (DDG 67). He also coordinated internal and external media coverage of embarks by dignitaries, foreign military officers, celebrities and professional athletes.

In July 2002, Garrett was assigned to the staff of Commander, U.S. Naval Forces Central Command/Commander, U.S. Fifth Fleet headquartered in Manama, Bahrain, as the media operations officer. He organized more than 500 media embarks during Operations Enduring Freedom and Iraqi Freedom which yielded unprecedented live television coverage of U.S. Navy warships during combat operations. As a spokesman for the U.S. Fifth Fleet, Garrett escorted international media to coalition warships on patrol in the Arabian Gulf, showcasing the multinational maritime forces supporting Operations Enduring Freedom and Iraqi Freedom to millions of people worldwide.