Sangster held off Induna by a head while Sabrage finished third in the three-year-old classic.
Busuttin, who turned 32 on Tuesday, said the Derby winning result was "just fantastic - a dream come true."
"We were three deep the whole way and I though we were no hope at the 600 metres. Hughie (Bowman, jockey) said before race that he didn't want to hit the front until the 200 metre but he was in front at the home turn," Busuttin said.
"We planned for this day for a long time and to his credit the horse delivered. We had a few hiccups along the way but he's got the race that counted."
Busuttin trains Sangster for a syndicate which paid $19,000 for him at the Karaka ready-to-run sale last November.
'He was a big skinny horse but we gelded him and he filled out and he showed he could gallop from day one.'
Busuttin grew up with racing in his blood. His father, Paddy, is currently training in Asia and has been one of New Zealand's leading trainers for many years. His best horse was top stayer Castletown which won three consecutive Wellington Cups over the then distance of 3200 metres.
The historic Melbourne Cup also over 3200 metres will be held on the next day of the Flemington spring meeting - the second Tuesday in November. Another Kiwi? probably not, but it would be a good result.