Falkirk scored the opening goal for the fifth consecutive match, when Ryan Flynn started and finished a flowing move in the 27th minute, and this time held on for their first win in seven games.
The victory moved the Bairns one point behind Kilmarnock, who host Aberdeen tomorrow, and Pressley could not hide his delight after the final whistle.
"I've almost been like a broken record week after week, the performances have been exceptional and our desire has been exceptional," the former Scotland defender said.
"I'm so pleased for them because we finally got what we merited.
"Much was said about the standard of the pitch but you saw a team at the bottom of the league playing some excellent football, taking the ball in difficult positions and showing the confidence to express themselves.
"We also did the basics very well."
Flynn's goal came after an intelligent pass into the box by Colin Healy and a brilliant flick by Pedro Moutinho.
"That's what we encourage - interchanging positions, passing the ball, variation in our attack," Pressley said.
The Falkirk boss added: "We started the game with seven academy graduates - that might be an SPL record. It's testament to our football club and the investment in the academy."
Motherwell boss Craig Brown was disappointed with the way his side started the match as their European hopes suffered a blow with their first home defeat of 2010.
"Give credit to Falkirk, they came with a need to win and an urgency," Brown said.
"The difference was we wanted to win and they needed to win, and added to the desire they had, they got a very fine goal.
"It was a superb goal, great movement and great passing. It was a goal worthy of winning a game but from our point of view it was poor defensively."
Brown added: "We normally start the game with great urgency but quite unaccountably it was slack today.
"We didn't start with the appropriate aggression or determination. In all the games I have had here, we have started better than the opposition, even in away matches.
"We had one or two chances but at home we should have made more chances than we did."
Brown, who admitted the absence of Lukas Jutkiewicz with a knee injury was a major blow, also lost John Ruddy and Keith Lasley during the game.
He said: "Ruddy has a slight problem with his hamstring, he has had it a couple of weeks.
"Keith has gone for an X-ray just below his knee. The doctor thinks it's just bruised but he will have an X-ray as a precaution."