Geldenhuys played his 67th and final game for Italy in this weekend's defeat to Tonga.
South Africa-born Geldenhuys, who is on the books at Italian side Zebre, played his 67th and final game for Italy in this weekend's defeat to Tonga.
But the towering 35-year-old said he plans to make Italy his home.
"I came to Italy in 2005 and I will always be grateful to the country and all of Italian rugby for what they have given me," said Geldenhuys.
"Our kids were born here, it's our home and we'll be staying here in the future.
"Wearing the blue jersey and taking part in two World Cups was not something I imagined I'd be doing when I arrived to play for Viadana, and captaining the country that adopted me was a huge privilege," added Geldenhuys.
Italy capped their November test series with a 19-17 defeat to Tonga, having ended their 13-match wait to beat South Africa just a week earlier in Florence and started the month with a 68-10 defeat to New Zealand.
Saturday's defeat in Padua was Geldenhuys's swansong and Italy coach Conor O'Shea said: "We would have preferred to give Quintin a winning send-off, because his contribution to what is a new chapter for Italy has been immense.
"We will all miss him but I'm sure he will keep going strong for Zebre and help their younger players.
"We want to thank him for everything he's given to the national side."
Geldenhuys said he will now focus on helping Zebre, who play in the Pro12 league along with fellow Italians Treviso, and spend more time with his family.
"I want to dedicate these last years of my career to my club and to help Zebre as much as I can," he added.
"It will also give me more time to spend with my kids, who are growing up.
"But with Conor O'Shea at the helm, a new Italy side is emerging and I want to wish them all the best for the future.
"In the second row there are plenty of up and coming young players ready to jump at the chance. (Marco) Fuser has come on leaps and bounds and will continue to do so, and (Federico) Ruzza at Zebre has the tools to become an amazing athlete.
"It's time to give them their opportunity."