Andover won the toss in the semi-final clash and decided to bat.
Openers Eduardo Martins (19) and Sanjeet Garood (29) gave them a solid start.
Nyasha Mayavo then kept the scoreboard ticking over with 54 from 32 balls, which included seven fours and one six.
A quickfire 15 from Babu Veettill off just 12 balls helped Andover to 181-9 off their 20 overs.
Fred Egleston 2-6 off three overs and Dan Sumner 2-25 were the pick of the Park bowlers.
Rotherfield’s reply did not get off to the best of starts as both openers were back in the pavilion with only 13 scored.
Sam Ruffell (44) got them back on track, and this was followed by a match-winning innings from Mark Heffernan.
He smashed 78 off 45 balls and hit three big sixes as well as nine fours.
It was left to bowling heroes Egleston, not out 31, and Sumner, unbeaten on nine, to see them home with eight balls to spare.
Veettill and Byron James both took two wickets each for Andover.
Rotherfield will now contest the final against Hook and Newnham Basics on Monday, August 31 at May’s Bounty, which starts at 2 pm.
Meanwhile, in the Cyril Thompson Trophy, Kingsclere are the second side to make it into the last four after a four-wicket win over Yateley.
Yateley won the toss and elected to bat and scored 156-5 from their 20 overs.
Opener Jacques Pienaar got his side off to a good start with 37 from 32 balls.
Cameron Hume then took up the mantle and finished unbeaten on 51 at the end.
His innings of 39 balls included six fours and a six.
Dan Jones topped the bowling with 2-31, while there was one wicket each for Odhinn Moore, Ed Lyle, Chris Hanney, and Noah Deacon.
Ed Lyle proved to be the star of the Kingsclere reply with a superb innings of 83, which came off 45 balls and saw him hit 14 fours and two sixes.
He was well supported by Dan Jones, who finished 21 not out.
Kingsclere got home with three overs to spare as Joshua Gore took two wickets.
Kingsclere will now play East Woodhay in the first of the semi-finals at May’s Bounty on Monday, July 27.
The following night is the final Trophy quarter-final clash as Oakley take on Basingstoke Hockey.
The trophy games start at 5.45 pm with free admission.