Second round - beat Holland by 72 runs
Phil Weston's century was instrumental in Gloucestershire's comfortable 72-run win over Holland in Amstelveen as the defending champions progressed to the third round.
Gloucestershire posted 264-6 before bowling out the home side for 192 with three overs remaining.
Weston shared in a third-wicket stand of 139 with Matt Windows (62) while captain Mark Alleyne ended with figures of 4-33.
Third round - beat Hampshire by three wickets
Shoaib Malik held his nerve to steer Gloucestershire into the quarter-finals as they beat Hampshire by three wickets at Bristol.
Jon Lewis took 4-39 as Gloucestershire bowled Hampshire out for 154 and looked in control as Craig Spearman put on 76 in reply.
But Hampshire skipper Shane Warne revived his side with 4-23 as the defending champions slumped to 137-7, but Malik's unbeaten 28 pushed his side to 157-7.
Quarter-final - beat Middlesex by 16 runs
Gloucestershire clinched a semi-final showdown with Yorkshire as they beat Middlesex by 16 runs at Bristol.
The home side posted 239-8 with Craig Spearman top-scoring on 62 and Philip Weston scoring 54.
Mark Alleyne then took 3-31 as Middlesex replied with a total of 223-8 despite a half-century by Ed Joyce.
Semi-final - beat Yorkshire by five wickets
An unbeaten 143 from Craig Spearman helped Gloucestershire book a place in the final as they beat Yorkshire by five wickets at Bristol.
Spearman smashed four sixes and 14 fours off just 122 balls in Gloucesershire's 247-5.
Darren Lehmann hit an unbeaten 80 which helped Yorkshire to a decent total of 243-6 after they batted first, but it wasn't enough as Gloucestershire set up a repeat of last year's final against Worcestershire.