The 30-year-old had to develop a business plan during an eight-week period, then sell his idea to a panel of judges.
Mr Crosby, who works at Borthwick Estate in Carterton, earlier won the 2012 Markhams Young Viticulturist of the Year in Blenheim, which put him into this month's competition against other horticultural industries.
He has been making wine for eight years and says that experience helped give him the edge in the award.
"I think the earlier you start [making wine] the better. This is basically my career path and I couldn't be happier. It's an exciting industry."
The competition is managed by the RNZIH Education Trust on behalf of the sponsors including Agmardt, Fruitfed Supplies, and Turners and Growers.