Bora-Hansgrohe rider Postlberger, 25, won the 203km stage ahead of Caleb Ewan in second and Andre Greipel in third.
Last year's winner Vincenzo Nibali, Team Sky's Geraint Thomas and Colombia's Nairo Quintana all finished safely in the peloton in the opening stage of the race's 100th edition.
Saturday's second stage is a 208km ride from Olbia to Tortoli.
Postlberger's team-mate Cesare Benedetti took the Maglia Azzurra, the climber's jersey, after overhauling Daniel Teklehaimanot of Dimension Data.
Italian cyclists Nicola Ruffoni and Stefano Pirazzi were suspended before the race started, after returning positive doping tests.
The Bardiani CSF pair were due to ride in the Giro but world governing body the UCI said they were "provisionally suspended" after detection of the growth hormone GHRP.
Bardiani said both would be dismissed if the positive tests were confirmed.
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Thomas was the first British finisher in the race's opening stage, the Welshman finishing 18th, 10 seconds behind Postlberger.
All teams are racing with nine-man squads apart from Astana, who have only eight riders having left a space open following the death of Michele Scarponi on a training ride.
Team Sky's co-leader Geraint Thomas told BBC Wales Sport:
"It was OK. It wasn't too hard a day but the winds made it hard at times. It was all about getting through safely and saving as much energy as possible.
"The final was quite chaotic but fortunately I was OK. One [stage] down, 20 to go.
"It's all about good position and avoiding stuff like that [the crash towards the end]. A day like today, the pink jersey is up for grabs for the winner and there's a lot of stress.
"It wasn't one of the hardest stages so there were a lot of fresh legs at the end and a lot going on but, fortunately, the boys did a great job for me and [fellow leader Mikel] Landa. Perfect.
"I've done my fair share of that in tours in the past so I appreciate that and know how hard a job it is for them to do what they do. A good job but a long way to go."
Stage one result:
1. Lukas Postlberger (Bora-Hansgrohe) 5hrs 13mins 35secs
2. Caleb Ewan (Orica-Scott) Same time
3. Andre Greipel (Lotto-Soudal) Same time
4. Giacomo Nizzolo (Trek-Segafredo) Same time
5. Sacha Modolo (UAE Team Emirates) Same time

The firm said Christmas order numbers for this year had fallen and the Lincs Turkeys processing plant was no longer economically viable.
A consultation has begun with the workforce at the Grainthorpe factory.
The Lincs Turkeys farming operation, which in 2013 featured a company farmer in a Christmas advert for supermarket chain Waitrose, is unaffected.
A spokesperson for Bernard Matthews said: "The consultation is expected to result in a reduction of approximately 80 employees out of a [total company] workforce of 2,130."
The spokesperson said the decision "was not taken lightly", adding that "processing requirements will be integrated into the Norfolk and Suffolk sites".
Craig Leyland, of East Lindsey District Council, said the authority was standing by with advice.
"It is very difficult. We have tried to intervene in the past in situations where we have had these decisions being made. Effectively they are commercial decisions and it's very hard to intervene in that case," he said.
Bernard Matthews acquired Lincs Turkeys in 2010.
Austria's Lukas Postlberger won the first stage of the Giro d'Italia in Sardinia on his race debut.
[NEXT_CONCEPT]
Bernard Matthews is to close a processing plant in Lincolnshire with the loss of up to 80 jobs.