He blew 981mcg of alcohol per litre of breath - more than twice the 400mcg limit.
Unshaven and dressed in jeans and T-shirt, Seymour yesterday pleaded guilty in the Auckland District Court to drink-driving and failing to stop for police.
His lawyer, Melanie Coxon, said Seymour had been drinking with friends before "unwisely" deciding to drive home.
She gave a letter from Seymour to the court, and asked that he be sentenced to fines and disqualification.
Community magistrate Joanna Sihamu told Seymour he deserved credit for admitting guilt at the earliest opportunity after what she described as a "silly driving manoeuvre" and an "excessively high" breath-alcohol test.
She did not read his letter to the court, but told Seymour he was "endeavouring to work with your issues".
He was disqualified from driving for seven months and fined $950 with $132 court costs, on the drink-driving charge. He was convicted and discharged for failing to stop.
Outside court, Seymour refused to comment. He is leaving the Warriors to play for English club Hull on a three-year contract.
On October 29, Seymour married Roseanne Hogan in a ceremony that included a a stretch Hummer limousine and a chihuahua called Pinky as maid of honour.
His wife told the Woman's Weekly that Seymour - once described by Australian media as the bad boy of rugby league - had been on the straight and narrow since coming to New Zealand.
In 2006, Queensland police investigated allegations that Seymour had assaulted a female nightclub patron.
No criminal charges were laid after a police investigation failed to find sufficient evidence.
After being sacked by the Broncos he joined Cronulla for two seasons before being dismissed for three breaches of club disciplinary policy.
He joined the Warriors on a contract containing behaviour provisions.
