Born in Norrköping in Sweden, Olsson started his career at IK Sleipner. When he was 13, Olsson was offered a trial at English club Chelsea, however he didn't attend and subsequently moved to IFK Norrköping. When he was 16, Olsson garnered interest by European clubs such as Juventus and Ajax, as well as domestically from IFK Göteborg. However, he signed for Arsenal in 2011 for £200,000 after having spent two previous trial periods with Arsenal. While on trial at Arsenal, he played for Arsenal's under-16s against Crystal Palace and was invited to take part in the Ferrolli Cup and the Nike Cup as a result of his performances. Olsson revealed that it was the drive of Arsenal Academy manager, Liam Brady, who persuaded Arsène Wenger to sign him, that persuaded Olsson himself to sign for Arsenal.
Arsenal
Olsson first played for Arsenal during their 2013 pre-season tour of the Far East. He scored his first goal for Arsenal against the Indonesia national football team at Gelora Bung Karno Stadium, Jakarta following a cross from Tomáš Rosický. Olsson made his full competitive debut for Arsenal on 25 September 2013 as an 84th-minute substitute for Isaac Hayden in a LeagueCup game against West Bromwich Albion, in which he scored a penalty kick where Arsenal came out winners and proceeded to the next round.
On 2 September 2014, Arsenal announced that Olsson moved to FC Midtjylland in Denmark on loan until the end of 2014. He made his debut for the club in a 3–2 home win against OB Odense, coming on for Pione Sisto in the 78th minute. On 27 December 2014, the Danish club announced that a permanent deal had been agreed with Arsenal to make Olsson's loan move permanent, with the player himself signing a new three-and-a-half year contract.
On 7 January 2019, it was announced that Olsson had signed a contract with FC Krasnodar of the Russian Premier League.
International career
He has also represented Sweden at various youth levels and his style of play has been compared to former Swedish Arsenal players such as Freddie Ljungberg and Sebastian Larsson. In January 2015 Olsson received his first call up to the senior Sweden squad for friendlies against Ivory Coast and Finland. However, in his first training session with the team he broke his leg. Olsson was, in May 2017, called up to the Sweden's squad for the 2017 UEFA European Under-21 Championship to be held in Poland. On 20 November2018, Olsson played his first competitive match for Sweden against Russia at Friends Arena in Stockholm, in the 2018-19 UEFA Nations League. Olsson started in the midfield and played almost the entire match. It ended as a 2-0 victory for the home side, which earned Sweden promotion to League A in the next edition of the tournament, as well as a play-off spot for UEFA Euro 2020.
