Simpson began the final day four from the lead and despite two early bogeys he began to establish himself as a genuine contender when he birdied the 6th, 7th, 8th and 10th holes to move to 1 over and was at that point within one of Jim Furyk's lead.
Just as important for Simpson as the brilliant mid round stretch would be the run of eight consecutive pars to finish and with nearly an hour to wait his fate, Simpson settled in to watch the just how Jim Furyk and Graeme McDowell in particular would finish the event off.
He spent a brief time in one of the television booths then headed to the locker room where he and his wife sat and watched a video of his son but kept a watchful eyes on proceedings on the golf course.
McDowell and Furyk had begun the day in the lead but although Furyk made a solid start, the same could not be said of McDowell who made the turn in four over par 38 and at that point he had fallen three shot behind Furyk.
McDowell would however bounce back with birdies at the 11th and 12th holes and it soon became apparent he and Furyk were the only players Simpson needed to be concerned about.
A birdie at the 17th by McDowell had he and Furyk needing to birdie the final hole to catch Simpson but when Furyk found an impossible lie in the greenside bunker his chance was gone.
McDowell though had one last chance to force a Monday playoff with a twenty five foot birdie putt at the last but it was never on line and the title had gone to Simpson.
Simpson has emerged as one of the elite of the game over the past two years making it to the Presidents Cup side in 2011. He has now won three times on the PGA Tour and although he missed the cut at both the Players and the Memorial events, his form leading into the event was not quite as bad as it might have apeared.
"The first cut I missed was at The PLAYERS, said Simpson. "I actually played pretty well that week. I had a tough finish. Then had two weeks off and worked on a lot of things and my golf swing, and one move in particular that I kind of perfected, but it produced another bad habit, which we saw at Memorial. And I hit it terribly.
"But it was a blessing in disguise. If I had showed up at Memorial and hit it well, we would never have noticed that move I was working on.
"My caddie, Paul, flew back to Charlotte with my wife and I and stayed a couple of days in Charlotte over the weekend at Memorial and we worked hard on weeding out that bad habit I had picked up.
"Last week I went to Pinehurst with five of my buddies and we played golf for four days straight. And I honestly didn't do a whole lot of practicing once the Pinehurst trip came around. It was needed for me coming into a Major was just getting my mind off things and just go and play golf.
"I think for me this week, starting I got here Monday, and I think every day my game got a little better, said Simpson when asked about his week. "I hit it really well yesterday. The first few days I putted well and hung in there. Yesterday I hit it well and made me get excited for today.
"Today I had the best warm up I had the whole week before the round. You know, this is only my second U.S. Open and so I told myself don't get too excited, don't try to win. You've got to go out there ask try to make pars, and that's what I did. And luckily I made some putts, and got a couple under out of it."
"To be honest, I never really wrapped my mind around winning. This place is so demanding, and so all I was really concerned about was keeping the ball in front of me and making pars. You hear all the guys say it, but it's so true, the course is so hard you don't know if you're going to make three or four bogeys in a row.
"Today I was 2 over through 5, but I didn't think anything of it because I knew I had 7 coming up and a few other birdie holes in the back. I definitely thought about winning and wanted to win, but I was just trying to keep my mind focused on the hole that I was playing and just somehow make pars."
"If I was honest with you I believed in myself I could win a Major, but maybe not so soon. This is my fourth or fifth. And I just gained all the respect for the guys who have won multiple Majors, because it's so hard to do. The level of pressure is so much greater than a regular event.
"I got a nice, hard hug from my wife. But it was. It hasn't set in yet. Greensboro, my first win hasn't really set in, because I was the overnight leader. And I won by three. And I just kind of dreamt it up in my head that I was going to win there.
"This feels much different. It hasn't sunk in at all. I'm sure we'll celebrate on the plane back tonight. I look at my wife and said, "I don't think you'll be able to sleep now."
I can't sleep on planes, anyway, so I'm sure I'm not going to sleep any. When Graeme missed on 18 and I realized I had won, I just kind of shook my head in disbelief. I couldn't believe it actually happened."
Michael Thompson was one of the surprises of the week leading after round one with a best round of the week 66 and although he fell off the pace through rounds two and three he was perhaps even more impressive today with his final round of 67 to share second place with McDowell.
John Senden (see earlier story) finished as the best of the Australians when he just edged out Adam Scott to finish in a share of 10th position, his best finish at the US Open and his second best in a major championship.
Scott recovered from a slow start to the event to record three consecutive rounds of 70 and tie for 15th.