Erik Botheim started his career at
Lyn and made his senior debut at 15 years old in June 2015, when he came off the bench against
Ullern in a match that ended 2–2. He scored his first senior goal in October 2015, when he scored in Lyn's 9–2 win over
Holmen. In July 2016, Botheim signed for
Rosenborg. He made his debut for Rosenborg on 26 April 2017 in the first round of the
Norwegian Football Cup, when he started away to
Strindheim in a match that ended with a 2–0 win. Later that season, on 17 September 2017, he got his league debut for Rosenborg against
Vålerenga, coming on for
Anders Trondsen after 81 minutes in a game Rosenborg won 3–0. He scored his first
Eliteserien goal against Tromsø on 7 July 2018. A year later, on 10 August 2019, Botheim scored his first hattrick, again scoring against
Tromsø. On 15 February 2021, Botheim agreed a mutual termination of his contract. He joined
FK Bodø/Glimt. On 21 October 2021, Botheim scored two goals in Bodo/Glimt's 6–1 drubbing of
José Mourinho's
Roma in the
UEFA Europa Conference League. On 22 December 2021, he signed a 3.5-year contract with Russian club
Krasnodar. On 3 March 2022, following the
Russian invasion of Ukraine, Krasnodar announced that his contract was suspended and he would not train with the team, but the contract was not terminated and remained valid. On 18 May 2022, his contract with Krasnodar was terminated. On 7 July 2022, Botheim signed a contract until 2026 with
Salernitana in Italy. On 31 January 2024, Botheim signed a four-year contract with
Malmö FF. On 24 May 2024, Botheim scored a first-half hat-trick in a 5–0 win against
Kalmar FF, marking his eighth
Allsvenskan goal of the season. On 3 October 2024, he scored 2 goals in
Malmö FF's 2–1
UEFA Europa League against
Qarabağ, one of them being an acrobatic kick from
Gabriel Busanello's cross. Botheim was instrumental in
Malmö FF winning the
2024 Allsvenskan title, providing 12 goals and 5 assists in 30 games, as well as an additional 4 goals in the
UEFA Europa League. After a broken foot injury sidelined Botheim for most of the
2025 season, he returned in form in
2026. He scored 4 goals in the
2025–26 Svenska Cupen group stage, and netted instantly in his
Allsvenskan return in a 1–1 draw against
Örgryte IS on 5 April 2026.{{Cite web|first=Fredrik|last=Lindstrand|date=6 April 2026|title=Botheims hyllning: "Verkar som att vi är tillsammans i detta" ==International career==