Konta, now 28, who lost her first final in nearly a year in Morocco two weeks ago, maintained her fine form on clay with a 6-3 3-6 6-1 victory.
Konta told wtatour.com: "I just thought she (Pliskova) didn't really have a let-down in the whole match". Nadal won the first game 6-0. Especially in this tournament, it means quite a lot to me because I never played well.
"I was a little bit nervous today, it's a final so you have to be".
Konta became the first British woman to reach the final of the tournament since Virginia Wade in 1971.
Nevertheless Konta, who turned 28 on Friday, will take plenty of positives from her unexpectedly strong clay court season ahead of this month's French Open, in which she is yet to win a main draw match in four attempts.
Pliskova's victory will move her up to No. 2 in the rankings and makes her one of the contenders for Roland Garros.
Pliskova threw her racket in frustration after failing to convert a third break point in game seven, but a brilliant forehand saw her get the job done at the fifth time of asking in the set. Konta has now won 11 of her last 12 matches that have gone the distance and has produced a combined 11 breaks in her last two matches.
The 19-year-old levelled the match at one set all by breaking Konta for the second time in the ninth game. This will be the first meeting on clay and all previous five matches took three sets to be decided.
The victor of an astonishing 11 men's singles crowns at Roland Garros, which will host the year's second grand slam from next Sunday, Nadal had endured an unusually underwhelming clay-court season prior to facing Djokovic, losing semi-finals in Monte Carlo, Barcelona and Madrid.
"She loved clay so she knows exactly what I should do", Pliskova said of Martinez.