The Middlesbrough striker is leaving New Zealand's training base in Austria to fly back to England for the wedding, the New Zealand Press Association reported on Friday.
Killen, who scored in the 2-1 friendly defeat by Australia in Melbourne on Monday, will be available for his country's final two warm-up games against Slovenia and Chile.
The clash of dates could have been far worse with Killen saying the date of his wedding had been arranged more than a year ago, long before New Zealand qualified for the World Cup.
The All Whites have been drawn in Group F for the June 11-July 11 World Cup in South Africa alongside holders Italy, Paraguay and Slovakia.
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