The 19-year-old edged out Australians Cameron McEvoy and James Magnussen in the 50 metres freestyle in a time of 21.92 seconds to add to the 50 butterfly gold he won on Friday.
On a night where Games-best times, record-breaking medal hauls and exhilarating relays brought the curtain down on the event, the session belonged to England and it was a sparkling performance that stood out.
Proud, who also won a bronze in the 4x100 freestyle relay, had never reached a final at a major competition before arriving in Glasgow.
"I couldn't have asked for anything more," he told Reuters. "Coming into these Games it was all about preparation and trying to learn as much as I could.
"There are some great swimmers here and I didn't expect to make a final, let alone get a medal. To become the Commonwealth champion for the second time is unreal.
"It's given me that confidence boost I need for Rio 2016," said Proud in reference to the Olympics. "I just need to make sure I step up when it's needed - it's a big learning curve for me."
In addition England beat Australia to the men's 4x100 relay crown in a Games-best time to snatch a 10th gold in the pool, matching their best total from Manchester 2002.
Wales also enjoyed a good night, capturing a gold, silver and bronze.
The country's 40-year wait for a female swimming champion at the Games was ended on Monday when Jazz Carlin won the 800 freestyle.
A day later compatriot Georgia Davies captured the 50 backstroke title in a Games record 27.56 seconds, making it the first time Wales have clinched multiple swimming golds in the competition.
The 23-year-old had already won a silver in the 100 on Saturday and secured another medal by overcoming her rival and friend Lauren Quigley of England.
"I'm so happy especially with the two of us battling against each other. Now we stand on the podium next to each other having both smashed the old British record," Davies told the BBC.
"It is back to training tomorrow but I don't want to stop swimming now because I want the fast times to keep coming."
Carlin added another silver for Wales when she finished behind New Zealand's Lauren Boyle in the 400 freestyle, a reversal of the 800 result the previous day.
Buoyed by his compatriots, Daniel Jervis picked up the bronze in the 1,500 freestyle to take Wales' medal haul to seven, their best-ever swimming display in the Games.
Canadian champion Ryan Cochrane successfully retained his 1,500 title while Mack Horton finished second for Australia.
As if to put things in perspective, South African Olympic 200 butterfly champion Chad le Clos matched Wales' total when he won bronze in the 200 individual medley and team bronze in the 4x100 medley to take his personal medal haul in Glasgow to seven.
Both 4x100 medley relays provided a spectacular end to the evening as the crowd roared the teams on in two frantic races matched only by the atmosphere at the Tollcross Swimming Centre.
Australia took the women's race on the last leg to set another Games record time ahead of England and Canada.
- Swimming & Diving
- Sports & Recreation