On 18 January 2010, he made his first international cap for South Korea at the friendly match against Finland. In May 2012, Park was recalled to the national team for their World Cup qualifying matches against Qatar and Lebanon.

In June 2011, Park Joo-Ho signed a four-year contract with Swiss Super League club Basel. In July 2011, he played with his new club in the Uhrencup and won the tournament. He played his League debut on 20 August 2011 in the 3–1 away defeat against FC Luzern. He then established himself as Basel’s first choice left back, and helped his team become the first Swiss club to advance to the knockout stages of a UEFA Champions League. At the end of the 2011–12 season, Park won the Double, the League Championship title and the Swiss Cup with the club.

The following season Basel had to rotate their players a lot because they played twenty European games, Champions League qualifiers and Europa League. Park lost his first-choice place in their defense, but still came to 21 League matches. Park scored his first league goal for Basel on 21 April 2013, in the 2–2 away draw against Thun. At the end of the Swiss Super League season 2012–13, Park won the Championship title and was Swiss Cup runner up with Basel. In the 2012–13 UEFA Europa League, Basel advanced to the semi-finals, there being matched against the reigning UEFA Champions League holders Chelsea, but they were beaten 2–5 on aggregate.

On 17 July 2013, 1. FSV Mainz 05 announced the signing of Park on a full transfer from Basel. He signed a two-year contract through June 2015 with a club option for an additional two years.

On 28 May 2014, Park replaced injured Kim Jin-su, and joined the South Korean squad for the 2014 World Cup in Brazil. However, he did not play in any matches and South Korea finished at the bottom of their group. Later that year, he was one of the three over-aged players in the squad for the Asian Games in Incheon but played in a less familiar defensive midfield role as Kim Jin-su was preferred at left back. He scored in the Round of 16 match against Hong Kong and started in all matches in South Korea’s run to the gold medal. The win also allowed Park to be exempted from the two-year mandatory military service and continue his career in the Bundesliga.

On 17 September 2015 Park scored his first competitive goal for the club in a last-minute goal in the third minute of stoppage time sealing a 2–1 win over FC Krasnodar in the 2015–16 UEFA Europa League. At the beginning of the 2017–18 season, Park was sent to the club’s reserve team on behalf of new head coach Peter Bosz. On 3 December 2017, Park left Dortmund.

On 18 December 2017, Ulsan Hyundai announced the signing of Park on a full transfer from Borussia Dortmund which he left. He signed a four-year contract through December 2021. He was appointed a vice-captain ahead of the 2019 season.

In May 2018, he was named in South Korea’s preliminary 28-man squad for the 2018 FIFA World Cup in Russia. He made the final 23-man squad. However he sustained a thigh injury during the group stage match against Sweden and was ruled out for the rest of the tournament.

Park met his Swiss wife Anna while playing for FC Basel, where she was working at the stadium cafe. They have three children, daughter Eden/Na-eun (born in 2015), and sons Aciel/Gun-hoo (born in 2017) and Élyséen/Jin-woo (born in 2020). After previously keeping his family out of the spotlight, Park and their oldest two children joined the cast of The Return of Superman in 2018.