Penney played four years of college basketball for the Wisconsin Badgers between 1999 and 2003, where he was twice named first-team all-conference and as an all-American.

He went on to play professionally in Spain, the NBA Development League, Israel, Lithuania, Germany and Turkey.

Born in the Auckland suburb of Milford, Penney attended Westlake Boys High School and played junior basketball for the North Harbour Basketball Association, joining their New Zealand NBL team, the North Harbour Kings, in 1998 as a 17-year-old.

[2][3] As a freshman playing for the Wisconsin Badgers during the 1999–2000 season, Penney had a minimal role under coach Dick Bennett, but still helped his team reach the NCAA Final Four while averaging 3.7 points and 1.4 rebounds in 34 games.

He averaged 16.2 points and was second on the team with 6.0 rebounds per game, as Wisconsin won the Big Ten regular-season title outright.

For his senior-year efforts, Penney earned first-team All-Big Ten honours again and was named an honorable mention All-American.

On 1 September 2003, he signed with the Timberwolves, but did not make the team's final roster as he was waived on 23 October prior to the start of the 2003–04 NBA season.

On 3 November, he signed with the Miami Heat and made his NBA debut that same day, scoring three points in 14 minutes of action against the Dallas Mavericks.

The following day, he made his second appearance for the Heat, but record no stats in just four minutes of action against the San Antonio Spurs.

[7] Following his release from the Heat, Penney moved to Spain and signed with Gran Canaria for the rest of the 2003–04 season.

On 4 November 2004, he was selected with the sixth overall pick in the 2004 NBA Development League Draft by the Asheville Altitude.

[8] He was waived by the Clippers on 3 January 2005 and returned to the Asheville Altitude to play out the season and help the team win the 2005 NBA D-League championship.

On 5 August 2005, Penney signed a two-year deal with Maccabi Tel Aviv of the Israeli Basketball Premier League.

[14] Following the conclusion of the 2009–10 NBL season, Penney returned to the United States, and on 24 March 2010, he was acquired by the Sioux Falls Skyforce of the NBA Development League.

[38] He helped the Hawks finish the regular season in third place with a 17–11 win–loss record, booking themselves a semi-final clash with the second-seeded Perth Wildcats.

[49][50] Penney debuted for the New Zealand national basketball team in 1999 at the age of 18, going on to represent the Tall Blacks at two Olympic Games (in 2000 and 2004) and four world championships (2002, 2006, 2010 and 2014).

Penney was part of the Tall Blacks' memorable 2002 World Championships campaign as they surprisingly finished fourth.

[51] Penney led New Zealand to victory in the 2009 FIBA Oceania Championship, beating Australia 177–162 on aggregate, after the two-match tie was drawn 1–1.

[51] Penney participated for New Zealand at the 2014 FIBA Basketball World Cup in Spain and averaged 10.8 points and 4.5 rebounds in six games.

[56] In August 2019, Penney was appointed as director of player development and coaching staff consultant at the University of Virginia.

[60] Penney did not continue with the program following the 2019–20 season due to the COVID-19 pandemic, leaving him stuck in New Zealand after the borders closed.

[61] In November 2023, Penney joined the Wisconsin Badgers men's basketball team as special assistant to the head coach.