Giffey and his UConn teammates Shabazz Napier and Tyler Olander are the only Division I men's basketball players in history to have won national championships as freshmen and seniors.

After winning the tournament, he said, “It was such an emotional time for me, that this university, this team, became such a big part of my heart and became so close to me that it never crossed my mind to leave this place.

[5] In the semifinal game of the 2014 American Athletic Conference men's basketball tournament Giffey scored a career-high 24 points, including 6 three-pointers, to help Connecticut defeat Memphis 72–53 on 14 March 2014.

[15] Giffey first represented Germany in international competition at the youth level, during the 2007 FIBA U16 European Championship Division B.

[18] Giffey's first tournament with the senior Germany national team came at EuroBasket 2013, where he contributed with averages of 9.2 points and 3.2 rebounds per game.

[19] The next international tournament for Giffey with Germany, would occur six years later, at the 2019 FIBA World Cup, where he played a limited role during the competition.

[21] In 2022, Giffey helped Germany earn a bronze medal finish at the EuroBasket, producing 5.9 points and 1.9 rebounds per game.

[22] The following year, he was a member of Germany's 2023 FIBA World Cup title winning team, averaging 3.1 points per game during the event.