It was Howell's first European Tour victory for over seven years - the last coming at the 2006 BMW PGA Championship - and, afterwards, he could barely contain his delight.
"It's been a long time coming," said the 38-year-old. "I'm hoping this is going to be huge for me in many ways, because I have had many chances to win and I haven't been able to do it.
"All week I was nervous, I can't explain why. We all know it's a big week and we've all got lots to play for, but today I found a little more inner strength. I still struggled a little bit to get the pace on the greens under the intense pressure and all in all, I was really pleased with how I stayed in control and kept controlling my swing and holed the ones that I had to right at the end.
"It's been an interesting seven years. I lost my way in life and on the course, as well, but now things are really good at the moment and I'm in a really happy place."
Howell had a five-under-par final round of 67 for a 23-under-par total of 265. After completing the front nine in just 31 strokes, he held on to play the back nine in level-par to fight his way into the play-off. He even coped when his drive at the 18th in regulation finished on the road. "I noticed my caddie Steve was having a bit of a mini tantrum himself when I ended up on the road there," said Howell afterwards. "That was obviously a little bit of a mistake."
"Hats off to David, he played great, made a nice birdie in the play-off and congratulations to him," said Uihlein
Howell was the winner but it was the end of an amazing few days for 24-year-old Uihlein. In the second round at Kingsbarns, he missed scoring the first 59 on the European Tour by inches as his putt on the final hole drifted left. The following day at St Andrews, he holed a 47-yard wedge shot for an eagle on the final hole to put him within two of then leader Tom Lewis.
In the final round, after a poor start when he lost a shot to the field at the first, he fought his way back with a 69 to get into the play-off, but he rued a missed four foot putt on the 16th and a 20-foot putt to win on the 18th in normal play.
Uihlein said: "Hats off to David, he played great, made a nice birdie in the play-off and congratulations to him. He made more putts than I did at the end of the day. I just didn't make the putts when I needed and that's the way it is."
One shot behind Howell and Uihlein were England's Tom Lewis following an excellent eight-under-par 64, and Ireland's Shane Lowry, with a 68.
Lewis, who had the lead after the second round, said: "I played well all week. It was just a shame a couple more putts couldn't go in and I messed up a couple of holes at Carnoustie yesterday ."
Meanwhile, Bradley Neil, the 17-year-old Scottish Boys champion, missed birdie putts on both the 17th and 18th holes as he and American partner Uihlein were forced to settle for the runners-up spot in the team competition on 38-under-par.