The 23-year-old, who at 6ft 3ins normally towers above most, jokingly tried to bulk himself out as he stood side by side with the players at a media photocall.
He raised his shoulders near his ears and, nodding towards England centre Will Greenwood on his right, laughed and remarked: "I've got to look bigger."
William, who is second in line to the throne, met Greenwood, Brian O'Driscoll, Gareth Thomas and Gordon Bulloch - representatives for each of the four Lions international teams - in the lobby of the squad's hotel in Wellington.
He earlier jetted in to the country ready for a 10-day tour of the Pacific Ocean islands where he will watch the Lions' second and third Tests.
Despite normally dealing with the much more fearsome All Blacks, the players, in their familiar red and blue Lions tops and jackets, seemed a little stunned when faced with the barrage of flash photography from the royal media pack.
"Whoa, whoa," Welsh skipper Thomas remarked, blinking into the lights.
William commiserated with injured O'Driscoll, whose right arm was in a pink foam sling, saying: "Bad luck, old mate".
The centre, who has been replaced as Lions captain by full-back Thomas, suffered a dislocated shoulder when two All Blacks players tipped him headlong into the turf during the first Test.
O'Driscoll, who has said he is gutted his tour is now over, joked, looking at his arm: "I thought it feels good - maybe it will be okay for the second game".
The Prince was greeted at the Intercontinental hotel by coach Sir Clive Woodward and tour manager and ex-Lions star Bill Beaumont.
Prime Minister Tony Blair's former spin doctor Alastair Campbell, who is now acting as a media consultant to the Lions, was also present for the brief photocall.
The Prince then headed off with the players for a team lunch ahead of a training session with them on Friday.
Scottish captain Bulloch said afterwards that the Lions were glad to have his support.
"Hopefully he'll come out and kick a ball about. He's meant to be quite good," the hooker added.
William will join fans by cheering on the Lions in Saturday's second Test against New Zealand, which follows the disappointing 21-3 defeat in the first.
During his stay, William is carrying out his first solo official public engagement.
On behalf of the Queen, he will mark the 60th anniversary of the end of Second World War by meeting veterans and laying a wreaths in Wellington and Auckland.