The victory, in 11hr 6min 51sec, was a breakthrough for the 26-year-old, who later referred to the event as the ''Holy Grail'' of multisport.
Currie praised the support of his family and, in particular, wife Sally, who is expecting the couple's second child in April.
He also gave special mention to defending champion and mentor Richard Ussher.
''Richard has just been incredible for me,'' Currie said.
''This year is something that I would not have believed would have happened for me. I've been pretty much non-stop racing and travelling around the world, and a lot of that is because of Richard. He chose me to race in his team, and has helped me out heaps.''
As Ussher crossed the finish line in second place, 6min 14sec back, Currie was one of the first to congratulate him.
Currie was involved in an initial group of 11, who set off from the start on Kumara Beach at breakneck speed.
He put his running ability to good use on the 33km alpine running stage, spreading a lead group that contained Ussher, Dougal Allan (Wanaka), Trevor Voyce (Nelson), Sam Clark (Whakatane), birthday boy Luke Vaughan (Christchurch), Dan Moore (Picton), and JJ Wilson (Christchurch).
Currie opened up a 6min lead over the run up to Big Boulders, but his race almost came unstuck when he ''smashed'' his knee just above Doreen Stream.
''I had to stop and walk for a couple of minutes.''
Currie regained his composure and was back at full pace when he reached Goat Pass, learning he had extended his lead to 7min.
He forged further ahead over the descent to Klondyke, and sped through transition to the 15km bike stage.
He continued his form in the kayak, reaching the water at Mt White Station Bridge 12min clear of Allan and Voyce, with Ussher a further 2min 30sec behind.
Currie, mindful of being overtaken by Ussher at this stage last year, kept up the tempo. Ussher recorded the fastest kayak time (4hr 8min 56sec), overtaking both Voyce and Allan and came within 6min of Currie on the 70km bike to the finish.
It was not enough, however, as the Wanaka man stayed composed on the bike and then ran down the finishing chute on Sumner Beach to break the tape.
''This is just amazing for me,'' Currie said.
''Last year, I blew myself to pieces, pretty much. I knew what I had to do to win today and I wasn't going to go out there to come second. I just tried to do everything I could, too, and it paid off.''
Coast to Coast organiser Robin Judkins said Currie had run a ''fantastic'' race.
''What a family history. His brother [Glen] came third three years ago. This boy is really, really good.''
Sophie Hart (Nelson) took charge on the 33km alpine run stage to open up a commanding lead and power away to a convincing victory in the open women's section of the Longest Day.
Hart's day could have panned out a lot differently after the chain came off her bike on one of the steep climbs on the 55km stage between Kumara and Aickens.
Quick reactions and a determination to rejoin the bunch saved her day, as she overcame a 33sec deficit to defending champion Elina Ussher and opened up a 15min 12sec advantage going on to the river stage.
Hart extended the margin by 12min before the long bike to the finish at Sumner, crossing the line in 12hr 36min 19sec. Ussher was second in 13hr 11min 49sec.
Hart played down the pre-race hype of the prospects of a battle between herself and Ussher.
''Elina is such a tough competitor. I couldn't really hide so much, like I did last time,'' she said of her 2011 victory.
''I'm stoked to be able to put it all together today.''
Despite an indifferent kayaking stage, Dunedin audiologist Anthony Rowcroft recorded a top result on Saturday.
Contesting the individual two-day section, Rowcroft finished second in the veteran men's section and 18th overall in an impressive first-up time of 14hr 6min 21sec.
''I had a shocking paddle. I had three swims, which was a little disappointing,'' Rowcroft said.
