Foster's win in the men's 50 metres freestyle followed earlier victories by Karen Pickering (women's 200m freestyle) and Nick Gillingham (men's 200m breaststroke).
And with silver medals coming on the final day from Fraser Walker in the men's 200m medley and Martin Harris in the men's 100m backstroke, Britain's total of eight medals equalled their best return at a world championships, which came at the World Long-course Championships in Colombia in 1975.
While a significant number of the world's leading competitors have been missing from these inaugural short-course championships, this could not detract from the quality of any of Britain's three gold-medal performances.
The 50m freestyle in a short-course pool was tailormade for the 6ft 5in Foster - the world record-holder - with his razor-sharp starts and powerful turns.
Accordingly, the 23-year-old from Southend surged to his first major title in 21.84sec - 0.24sec outside the world mark he set at Sheffield last February.
Foster had been disqualified for a false start after he finished fourth in the 50m freestyle final at the European Championships in August. But he made no mistake yesterday and, after he had led going into the turn, held off China's Hu Bin, who was second in 21.93.
'I have never been so nervous before a race as I was before the start,' he said. 'I was trying to stay calm but I kept fiddling with my goggles.'
Walker, 20, from Fife, lowered his own British and Scottish record by nearly two seconds to 1:58.35 on his way to finishing second behind Germany's Christian Keller.
Martin Harris - who in his heats became the first Briton to beat 54 seconds for the 100m backstroke with 53.92 - finished second in the final in 53.93 behind Tripp Schwenk, of the United States.
There were also British records for Scotland's Graeme Smith, fourth in the 1500m freestyle final in 14:54.45, and Joanne Deakins, sixth in the women's 200m backstroke final in 2:09.99.
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