The efforts of the 27-year-old proved the difference as after a jump of 128m during round two he lost a ski on his landing but managed to keep his balance and avoid tumbling before the line.
After a poor jump from Norway, who were first until then, Fettner's composure gave the Austrians the lead and one that they wouldn't relinquish with Thomas Morgenstern and Gregor Schlierenzauer next to jump.
Austria finished with a winning total of 1135.9 points to maintain their run of victories from Oberstdorf 2005 while Germany claimed silver and Poland bronze ahead of Norway after a jury meeting.
Morgenstern contributed jumps of 121m and 129.5m despite suffering from a sprained ankle however he is adamant the injury won't be ruling him out for long with the World Cup set to restart next week.
"It was a pleasure to take part in the team competition. The fight for the top places was really close and we could enjoy it," said Morgenstern.
"I tried to make a telemark in the final round and then I felt some pain in my knee, but it won't be something serious."
Wolfgang Loitzl produced efforts of 130.5m and 128 m and Schlierenzauer contributed 124.5m and 129m while Fettner's opening effort was 125.5m as Austria retained their team title.
However Fettner's save wasn't the only drama as Norway, Germany and Poland battled it out for silver and bronze with the outcome still undecided until the last jumps of Anders Jacobsen, Richard Freitag and Kamil Stoch.
Stoch leapt 130m to earn Poland 1121 points while Freitag landed 129.5m as Germany surpassed them with 1121.8 while Jacobsen leapt 131.5m for what looked silver for Norway ahead of both.
But the results were checked again in the jury meeting concerning the gate compensation points of Anders Bardal's first jump and their final decision saw Norway miss out altogether as they finished fourth with 1117.3 points.