Nerves got the better of Randhawa, who blew off a good start to slip down the leaderboard, even though his exploit was good enough to finish ahead of the likes of Sergio Garcia (281) and Padraig Harrington (282) with a total of eight-under 280.
Among other Indians, Jeev Milkha Singh was the next best-placed at tied 33rd after turning in a two-under 70 for the second consecutive day. Jeev picked up four birdies against a couple of bogeys to finish with a total of three-under 285.
But the nightmare continued for Gaganjeet Bhullar and C Muniyappa, both of whom returned over-par cards yet again to sign off tied 74th with totals of 12-over 300. While Bhullar carded a 74, Muniyappa was even worse with a 79 on the final day.
Overnight tied sixth, it was a perfect start to Randhawa's day as he birdied the first hole. But his form dipped after that and he dropped a stroke on the fourth hole before stumbling to a double-bogey on the ninth to be two-over at the turn.
Randhawa conceded that the big occasion got to him after the good start. "I guess I was a little tentative today. I wanted to play well but I didn't hit the ball the way I wanted to. I lost a bit of focus in between. I guess the event got to me as suddenly I realised where I was and made a few mistakes," said the lanky pro.
On his way back, Randhawa parred the first four holes before finding a birdie on the 14th. For the third day in a row, Randhawa gained a stroke on the 16th hole to prevent an over-par card.
"It was nice to get a birdie on the first hole but I couldn't keep it up. It was a good experience. It has been a good week. I have kept my card in Europe, which I'm happy about.
"Now, I can go out and just play the game in the next few weeks. I need to get rid of this thing of trying to make a score and just go out to play golf. I think I realised that I need to be more mentally focussed to play my best golf. Today, I wasn't mentally there," he said.
The American world number two Phil Mickelson (69) clinched the title by a stroke after ending with a total of 17-under 271. South African Ernie Els, who fired a sensational nine-under 63 today, followed Mickelson at the second spot.
World number one Tiger Woods finished tied sixth with an even-par card, his worst of the week, in the final round. Woods finished with a total of 12-under 276.
'My dream has always been to play with Tiger'
Jyoti Randhawa ends 51st
Woods back at number one
Jeev Milkha Singh eyes major glory