Hernandez started his career withAtlético Madrid, where he made more than 100 competitive appearances, reaching the2016 UEFA Champions League final. He also won the2018 Europa League and theSuper Cup in the same year. He signed for Bayern in 2019, winning theBundesliga,DFB-Pokal, andChampions League in his first season as part of atreble. Hernandez returned to his home country and joined Paris Saint-Germain in 2023, where he won the Champions League again to complete a second treble in2025.
Hernandez made his senior debut on 26 April 2014, starting forthe reserves in a 0–1 away loss againstReal Sociedad B in theSegunda División B.[12] He appeared in three further matches duringthe season, as they narrowly avoided relegation; he also signed a new deal with the club in June, running until 2018.[13]
On 6 August 2016, Hernandez signed a contract extension with Atlético until 30 June 2020.[19] He played a more important role for Atlético during the2016-17 season. Hernandez played in 22 matches in all competitions during the season. He was in the starting lineup in 20 of these matches.
During the2017–18 season, Hernandez was a key member of the team as he played in 44 matches in all competitions. Atlético reached the2018 UEFA Europa League final. He started and played the whole match against French club Marseille. Atlético won the match 3–0 and Hernandez won his first international trophy.[20]
Hernandez scored his first goal as a professional on 19 January 2019, in a 3–0 away defeat ofHuesca.[21]
On 27 March 2019, Atlético confirmed that Hernandez would leave the club in the summer of 2019. Atlético confirmed they offered Hernandez a contract extension, but he decided to sign forBundesliga clubBayern Munich. Atlético said that the German club activated Hernandez's release clause of €80 million.[22] During the medical examination by Bayern Munich medical staff, a damage to the medial collateral ligament in Hernandez's right knee was found. The injury required a surgical repair. On 28 March 2019, Hernandez had a successful operation on his right knee. The operation ended Hernandez's season with Atlético.[23]
Hernandez played in 14 La Liga matches and scored one goal. In all competitions, he played in 22 matches and scored one goal.
On 12 October 2019, Hernandez's former coach at Atlético, Diego Simeone, said in an interview withMarca that the left back's departure to Bayern had hurt Atlético a great deal: "The exit that hurt us the most was Lucas, who was a boy from the academy ... [It hurt] More than [Antoine]Griezmann," who left Atlético at the same time forBarcelona.[24]
On 27 March 2019, Bayern Munich announced that Hernandez would join the club on 1 July 2019 for a club record (and Bundesliga record) fee of €80 million, signing a five-year contract lasting until 2024.[25][26] He made his debut for Bayern on 10 August in a first round match againstEnergie Cottbus in theDFB-Pokal as an 89th-minute substitute.[27] On 23 August 2020, along with his Bayern Munich teammates, Hernandez became a Champions League winner after a 1–0 victory overParis Saint-Germain (PSG) in the final.[28]
On 3 November 2020, Hernandez scored his first goal for Bayern Munich in a 6–2 away win overRed Bull Salzburg in the Champions League.[29] In April 2021, Bayern were eliminated from the European competition in the quarter-finals by Paris Saint-Germain on away goal rule after a 3–3 draw on aggregate.[30]
Hernandez missed three league matches at the start of the 2021–22 due to a knee injury sustained during the postponedEuro 2020.[31] However, he was part of the team which reached the quarter-finals of the Champions League before losing to Villarreal 2–1 on aggregate.[32]
On 13 September 2022, Hernandez scored his first goal of the 2022–23 season from a header in a 2–0 win over Barcelona in the Champions League.[33] Two months later, he sustained a cruciate ligament rupture in his right knee during the2022 FIFA World Cup, which sidelined him for the rest of the season.[34]
On 9 July 2023, Hernandez signed forLigue 1 club Paris Saint-Germain on a five-year contract until 30 June 2028, for a transfer fee reported to be in the region of €40 million.[35][36]
He made his debut in a 0–0 draw againstLorient at theParc des Princes on 12 August.[37] On 4 October 2023, Hernandez scored his first PSG goal, a header in a 4–1Champions League defeat away toNewcastle United.[38] On 25 October 2023, Hernandez for the first time faced his younger brother,Théo, as an opponent playing competitive senior football in the Champions League group stage home game againstAC Milan, a 3–0 win for PSG.[39]
In the first leg of the Champions League semi-finals away toBorussia Dortmund on 1 May 2024, Hernandez tore his anterior cruciate ligament (ACL) in his left knee, ruling him out for the rest of the season.[40][41]
In March 2018, Hernandez was called up tothe senior team by managerDidier Deschamps forfriendlies withColombia andRussia.[43] He made his debut against the former, replacingLucas Digne for the last 14 minutes of the 2–3 loss inParis.[44] Hernandez was selected for the2018 FIFA World Cup.[45] He made his debut inthe competition on 16 June, playing the entire 2–1 group stage win againstAustralia;[46] he featured in all of the matches for the eventual champions, playing for the full 90 minutes in six of France's seven matches on their way to winning the tournament and came up with two assists, including one toKylian Mbappe in thefinal.[47][48]
In October 2021, ahead of theUEFA Nations League semi-finals againstBelgium, Lucas for the first time received a call-up to the national team fromDidier Deschamps together with his brother Théo; the two were later fielded in the 3–4–1–2 formation as a left center back and a left wingback, respectively, making it the first time they played together in a senior competitive game, which turned out to be a 3–2 comeback victory for France, with Théo scoring the winning goal in the 90th minute.[49]
Hernandez was selected for France's squad ahead of the2022 FIFA World Cup but suffered a ruptured anterior cruciate ligament 13 minutes into the first group match against Australia and was subsequently ruled out for the remainder of the tournament.[50] Théo substituted into the match for him after the injury and played out the remainder of France's World Cup 2022 run in his stead.[51]
Hernandez's father,Jean-François, was also a footballer who played as a centre back. Of Spanish descent,[52] he also played for Atlético Madrid;[53] Hernandez's younger brother,Théo, was also raised at the club, and played in the same position.[54] In an interview withMarca in October 2018, he stated that his family had not heard from their father for 12 or 13 years.[55] In 2022, French newspaperL'Équipe found that Jean-François – who went missing in 2004 – was living in Thailand, and had allegedly been legally blocked by his ex-partner from seeing their children.[56]
On 3 February 2017, Hernandez was arrested on suspicion of assaulting his girlfriend,[57] who was also summoned to appear in court.[58] Both Hernandez and his girlfriend, Amelia Llorente, were sentenced to 31 days of community service, while Hernandez was also served with a restraining order preventing him from being within 500 metres of Llorente.[59][60]
Hernandez was arrested again in June of the same year for violating the restraining order after he and Llorente landed together in Madrid, returning from their honeymoon. For this violation, on 13 October 2021, Hernandez was sentenced to six-months in prison by a Spanish court; Hernandez successfully appealed his sentence and was instead given a four-year suspended sentence and ordered to pay a €96,000 fine.[59][60][61]