The 35-year-old, who considered retiring at the end of last season with he and his wife expecting their first child, shot cleanly en-route to securing a maiden career victory in 48min 07.4sec.

The silver medal went to Czech Republic’s Ondrej Moravec, who was 3.3 seconds back.

France’s Martin Fourcade, winner of the last four major individual titles, was 21.2 seconds behind in the bronze-medal position with two penalties.

The first man out of the start gate was Russia’s Anton Shipulin, who won the most recent individual World Cup event in Antholz in Italy last month, but his two prone misses put him out of medal contention.

Fourcade started with bib number four and set the pace early in the competition, despite penalties in the two prone stages.

At one stage, it looked like the man to challenge the Frenchman would be Norway’s Johannes Thingnes Boe.

He took the lead after the second stage and skied well, but had penalties in the last two stages and fell back.

Moravec, meanwhile, shot clean for the first time in an individual event and finished with a comfortable advantage.

As he waited in the leader's lounge, Bailey was making his bid for his first victory and dropped the first 15 targets to take the lead by 12 seconds over the Czech.

The American calmly hit the last five shots, leaving with a 6.4-second lead that was cut to just 0.1 seconds with 1,100 metres remaining after he lost time going through the easier part of the 4km loop

Over the final stretch, he clawed back time and sprinted across the finish line to seal a memorable triumph.

"I am waiting for someone to wake me up," Bailey said.

"It’s all clichés; it’s unbelievable, it’s like a dream.

"It means so much because of all the hard work that went into this medal and all of the support that I've had - it has all paid off.

"It is special for me to share this medal with the staff from our team.

"I have wanted a World Championship medal for so long.

"It’s still sinking in."

Bailey's gold is the fourth medal for the US at the IBU World Championships, and the first since Tim Burke won silver in the same discipline in 2013. 

The two others were a silver for Josh Thompson in the individual competition in 1987, and a bronze for the women's 3x5km relay team of Holly Beatie, Julie Newman and Kari Swenson in 1984. 

Last year’s bronze medallist Sergey Semenov of Ukraine was fourth today, 45.5 seconds back with one penalty.

Germany’s Erik Lesser was 49.1 seconds behind in fifth, while Czech Republic’s Michal Krcmar shot clean but ended up in sixth, 52.3 seconds back.

Action in Hochfilzen is due to continue tomorrow with the women’s 4x6km relay competition.