Garnett enjoyed most of his tennis success while playing doubles. During his career he won 1 doubles title. He achieved a career-high doubles ranking of World No. 49 in 1993.
Garnett's highest singles ranking was World No. 203 which he reached April, 1989.
ATP Tour doubles finals (4)
|Outcome||No.||Date||Tournament||Surface||Partner||Opponents in the final||Score in the final|
|Runner-up||1.||1991||Charlotte, U.S.||Clay||Greg Van Emburgh|| Rick Leach
|3–6, 6–2, 3–6|
|Runner-up||2.||1991||Guaruja, Brazil||Hard||Todd Nelson|| Jacco Eltingh
|Runner-up||3.||1992||Charlotte, U.S.||Clay||Jared Palmer|| Steve DeVries
|Winner||1.||1992||Washington D.C., U.S.||Hard||Jared Palmer|| Ken Flach