The 29-year-old, from Pewsey in Wiltshire, was fastest in both runs in Winterberg, to claim a clear 0.22sec success over series leader and pre-race favourite Anja Huber, of Germany.
Rudman, second in the previous four rounds, closed the overall points gap on her rival to 36 points with two races to go, the two well clear of Canada's Melissa Hollingsworth, who is a further 95 points back.
Canada's Amy Gough was third in Winterberg, with Bath's Olympic champion Amy Williams, fifth in only her second race since returning to action following her Vancouver success.
"I love the way I'm sliding at the moment and I know the World Cup race is going to go right down to the wire," said Rudman.
"There has been some great racing between the two of us.
"I've come second overall for each of the last two season and both times I missed out in the last race.
"But I won both races last year on the two tracks that are left, so I hope this year is going to be the one for me.''
Rudman admitted she took some time to recover from her Olympic disappointment in Vancouver last year, when she failed to recover from a slow start and ultimately trailed in sixth despite setting down the quickest time of the fourth and final run.
"Vancouver was very frustrating because I couldn't get time on the track and I really needed one extra day to get it right," said Rudman, who had won an Olympic silver medal in Turin in 2006.
"I was really upset with the result but my performance didn't really reflect that.''
Rudman's World Cup quest will move on to St Moritz next week before the regular season concludes in Cesana.
The 2011 World Championships take place in Konigssee, Germany, next month.
January 2011: Williams 12th on comeback in World Cup
December 2010: Rudman claims another silver as Bromley takes bronze
December 2010: Rudman denied gold by superb Huber