Saka was born in Ealing, Greater London, and attended Greenford High School. He started his career with Arsenal's Hale End academy. Once he turned 17 years old, Saka was given a professional contract by Arsenal and promoted to the under-23 side. On 29 November 2018, Saka made his senior competitive debut for Arsenal in their Europa League match against Vorskla Poltava. He came on as a 68th minute substitute for Aaron Ramsey. On 13 December 2018, Saka made his first full home debut for Arsenal in their Europa League match against FK Qarabag. On 1 January 2019, Saka made his debut in the Premier League in a 4–1 win against Fulham after coming on for Alex Iwobi in the 83rd minute. Saka was rewarded for his efforts in Germany with his first Premier League start, in a 3–2 home win over Aston Villa. He then registered an assist for Pierre-Emerick Aubameyang, setting up the Gunners equalizer in a 1–1 draw at Old Trafford against Manchester United. Following injuries to Sead Kolašinac and Kieran Tierney, Saka began to establish himself as a regular in the Arsenal first team at left back. On 27 January 2020, he scored the opening goal in Arsenal's 2–1 FA Cup fourth round victory at Bournemouth after finishing a 22-pass move, as well as assisting the second goal, scored by Eddie Nketiah. The goal was later voted goal of the round by the BBC. After a two-week mid-season break, Saka marked his return to action at home to Newcastle United with an assist for Nicolas Pepe's goal. He then set up Alexandre Lacazette for his ninth assist of the season in a 1–0 win at Olympiacos in the UEFA Europa League. He then hit double figures for assists that season after crossing in for Nketiah in a thrilling 3–2 home win against Everton. Further performances against Portsmouth and West Ham United further strengthened his grip in the first team. On 1 July 2020, Saka signed a new long-term contract with Arsenal. Head coach Mikel Arteta praised Saka and said: "I think he represents every value that this football club stands for. He has come through the academy, and earned his respect with hard work and accountability and you can see the progression that he is having as a player but as well as a person." He scored his first Premier League goal for the club against Wolverhampton Wanderers, with a half volley beating goalkeeper Rui Patrício, in a 2–0 win.
