On 10 June 2017, Šimić signed with Melaka United after being dropped by Negeri Sembilan.[4] He made his debut for Melaka United in a 1–1 draw against PKNS on 1 July 2017.
Persija Jakarta
First tenure
On 27 December 2017, Šimić signed with Persija Jakarta after not reaching agreement with Kelantan FA.[5]
Šimić made his Persija debut in a pre-season friendly against Persika Karawang on 30 December.[6]
On 8 January 2018, Šimić made his first goal for the club in a pre-season tournament 2018 Suramadu Super Cup against Madura United, as his team drew 2–2.[7]
In 2018 Indonesia President's Cup, Šimić scored a brace in Persija's 3–0 final win over Bali United. He also won the best player title and became a top scorer with 11 goals at that tournament.[8] On 28 February 2018, Šimić made his international goal for Persija with scored a hat-trick in a 4–1 AFC Cup win over Tampines Rovers,[9] and a month later, he made his league debut in the 2018 Liga 1 for Persija on 23 March in a draw 0–0 against Bhayangkara.[10] On 31 March, Šimić scored his first league goal for Persija in the first half 1–1 draw over Arema, and in the second half, he also scored for the team, he scored in the 52nd minute, in which Šimić scored 2 goals and Persija won over Arema 3–1 at the Gelora Bung Karno Stadium.[11][12]
On 10 April 2018, he scored a quat-trick as Persija claimed a 4–0 win over Johor Darul Ta’zim in the AFC Cup.[13] Šimić also became the first player to scored a hat-trick twice and a quat-trick in 2018 AFC Cup.[14] In 2018, Šimić brought Persija Jakarta to their first Liga 1 title and their eleventh Indonesian league title overall (including those Persija won in the Perserikatan era).
Šimić then won the Golden Boot award after he finished the 2019 season as the top goal-scorer in the Liga 1 with 28 goals.[15]
On 2 October 2021, Šimić scored his goal for Persija against Persiraja Banda Aceh as his team won 1–0, Persija's victory over Persiraja was determined by a Šimić goal through a penalty kick in the 70th minute, Simic's goal is also his 50th record during strengthening with Persija Jakarta.[16]
On 26 April 2022, Šimić terminates contract unilaterally with Persija after his salary was cut when 2020 Liga 1 was stopped.[17]
Second tenure
After a brief time playing with FK Radnički 1923 Keagujevac, Šimić returned to Persija right before the start of the 2023-2024 Liga 1 season.[18] He signed a two-year deal with Persija.[19] On his second start in a match against Bhayangkara which ended 4–1, Šimić scored his 99th and 100th goal for Persija in all competitions.[20]
International career
Šimić has represented Croatia internationally at U19, U20 and U21 level.