Berkshire will meet Lincolnshire for the Minor Counties Championship after beating Wiltshire by just four runs.
With Cheshire drawing against Cornwall, Berkshire clinched the Western Division title as they chase their first Championship title since 1953.
Captain Bjorn Mordt told BBC Radio Berkshire they used their MCCA Trophy final defeat by Devon as inspiration.
He said: "Everybody was down and I said I had a funny feeling the Championship was going to be ours this year."
He added: "We've won the Western Division and now we have a four-day match to compete for the Championship. It's fantastic for us."
In a match shortened by rain, Berkshire set Wiltshire 297 to win on the final day. By tea the visitors had reached 289-8 and victory looked assured, but Carl Crowe and James Morris each took a wicket to leave Wiltshire four runs short.
Berkshire manager David Morris said: "I can do nothing but pay tribute to the squad who've been absolutely amazing this year.
"Superlatives are often bandied around, but the team spirit and the performance of the 11 guys in this game and the two or three others who have played for us in the other games, I have nothing but the highest praise for."
He added that after the Lord's defeat earlier this month, it was nice to come in first.
"We came second at Lord's which was disappointing but a great occasion.
"Most of the lads took part in a karaoke competition and they came second in that as well - although the think they were robbed. But today we came first and that's the magic news."
The four-day final will take place at Falkland Cricket Club in Newbury, beginning on Sunday, 6 September.
Mordt urged his team to go on to win the Championship.
"The way we play cricket, I can tell you right now that it's not going to last four days - it'll be finished inside three because we're an attacking team.
"Two years ago we didn't win a game all season. Now we have to make sure that we follow through and win the whole thing."
~RS~q~RS~~RS~z~RS~30~RS~)