He returned to his Herne Bay home and read over his speech notes before heading to his New Lynn office.
"Tomorrow morning, we start our election campaign against the Key Government," he told the crowd.
At his side was wife Karen and his two sons, William and Cameron.
He became tearful when speaking of his family's support during his campaign.
Mr Cunliffe promised his campaign rivals, Grant Robertson and Shane Jones, "very senior roles" under his leadership.
In Wellington, Mr Robertson said he had been crunching the numbers in his parliamentary office on Sunday afternoon when it became apparent he had lost.
He walked down the hall to the Labour caucus room, where he told reporters: "Naturally I was disappointed. But this is a process that I back, and I back the outcome."
As colleagues and supporters Jacinda Ardern and Phil Twyford looked on, he said: "I have a lower profile than David, I haven't been in politics for as long - but I gave it my best shot."
Shane Jones had based himself at the Manurewa RSA with his loyal partner and nervous campaign manager Dot Pumipi.
A small group of about 20 were there in support, including his brother Peter Lucas-Jones and Mangere MP Su'a William Sio.
The results were announced to Mr Jones by phone from the party's general secretary Tim Barnett about 2.43pm.
Asked if he was disappointed, Mr Jones said: "I started this race as an underdog.
"And I really had a slightly different mission, which was to jolt our party and begin to talk in such a way that we made ourselves relevant again, not just to party members but to voters who seem to have walked away from Labour.
"And if I've contributed to that narrative then I have no doubt that I will be well regarded for that as time goes on."
- additional reporting: APNZ
