Read: PM's son cosy with president
Mr Obama said he would like to visit New Zealand by the end of his presidency which runs to the end of 2016.
Today's visit lasted an hour and 20 minutes. When the media was brought into the Oval Office for comments, Mr Obama spoke for six minutes 40 seconds, much of it in praise of New Zealand, and Mr Key for just one minute and 20 seconds.
Mr Key said the strong state of relations was "in a large part because of your leadership and your commitment to the NZ-US relationship."
"We appreciate all the things you do, the leadership you show around the world.
We know it is never an easy day in the office here at the Oval Office."
Mr Obama said under their terms of leadership, "I think it is fair to say the US New Zealand relationship has never been stronger."
"We share values. We have enormously strong people to people relationships.
We have excellent commercial ties and we have increasing consultations
and relationships between our militaries.
"All of those components have deepened throughout the course of our tenures here."
The top of their agenda was trying to get movement on the Trans Pacific Partnership Agreement among 12 countries, including both United States and New Zealand.
Mr Obama set a new goal today to get a deal finished to take to Congress before the Apec meeting in November.
That is likely to put pressure on Japan to stop holding up the deal through its failure to accept elimination on tariffs over time, or to leave the TPP.
Mr Obama made special mention of the fact that a New Zealand naval vessel will be tying up with the US at the Rimpac navy exercises in Hawaii this month - the first time in 30 years.
Read: Audrey Young: Ties strong between Key and Obama
Two years ago at the same exercise, New Zealand ships were taking part for the first time in 28 years but were confined to the civilian port.
Mr Key revealed today that the President had intervened himself to get the New Zealand ship into the naval port.
"I'm proud my home state of Hawaii is going to be welcoming a New Zealand ship coming into port for the first time in a couple of decades."
"We're very proud of that. I'm sure you'll get a good welcome when they come."
Mr Key revealed later that Mr Obama had intervened personally.
"The president himself thought it was pretty silly that a New Zealand naval vessel would be parked up at the commercial part of Honolulu Port and on a training exercise with the United States not be in that military facility.
The President himself intervened and had said 'that has to be resolved.'
"It's not a big thing itself but it's a tangible sign of the warmth of the relationship," Mr Key said.
Mr Key chose to echo Mr Obama's concerns about territorial disputes in Asia involving China and several other countries, and the need to follow international rule of law and the law of the sea.