Hundreds of invited guests have gathered at Britomart this morning to board the first electric train from the city.
The first service was due out of the station about 10am and traveled to Newmarket and back, with the return trip taking about 20 minutes.
Today's launch has prompted opposition parties to push for government funding for the City Rail Link.
Auckland Transport gave away 5000 tickets for rides on the train today, a day before normal paying services begin on the Onehunga line.
The $1.14 billion electrification project received the green light in 2007. Fifty-seven electric trains, each carrying up to 375 passengers, will eventually serve the network.
The Eastern line will get trains next, later this year. The Southern and Western lines will follow next year.
Auckland Transport spokesman Mark Hannan said electrification will cut about 10 minutes from the journey between Papakura and Britomart.
The planned city rail loop linking Britomart and Mt Eden would allow trains to move through Britomart, rather than having to backtrack, allowing more train services, Mr Hannan said.
"People will notice a small decrease in their journeys, but it's more likely they'll simply notice, in time, more trains.''
Mayor Len Brown today tweeted: "Making transport history in Auckland as we launch our new electric trains... next step, the City Rail Link.''
His thoughts have been echoed by the Labour and Green Parties.
Labour's Transport spokeswoman Darien Fenton said today's launch of the trains brought home the need to fast forward government funding for the City Rail Link.
"The city's transport problems can't wait for Gerry Brownlee to get over his stubbornness about rail.
"His antagonism was laid bare a couple of weeks ago when he told Parliament: `KiwiRail is fundamentally dead','' she said.
"The Government has set a passenger number target as their excuse for not funding the City Rail Link until 2020, but delaying it will cost taxpayers another half a billion dollars, cost Auckland investment potential and do nothing to ease congestion.''
A Labour Government would build the City Rail Link immediately, funding it 50:50 with Auckland Council, Ms Fenton said.
Green Party transport spokeswoman Julie Anne Genter said the trains would deliver cleaner and faster train services across the city.
"It is great that the Auckland rail network is finally modernising with the launch of electric trains today, the next step is to build the City Rail Link.
"The City Rail Link is the next essential step in creating a smarter, greener transport network that works for all Aucklanders.''
The rail link was critical to unblock the bottleneck at Britomart and get the full benefits of electrification, Ms Genter said.
"Compared to National's multi-billion dollar duplicate motorways, investing in Auckland rail is cheap and cost-effective.''
Transport Minister Gerry Brownlee was not immediately available for comment.