Born in Kaduna, Sadiq started playing football on the streets of his hometown at an early age. He later played for local team Kusa Boys, before joining the Future of Africa Football Academy and finally the Football College Abuja. In June 2013, Sadiq traveled with FCA to Croatia and participated at the Kvarnerska Rivijera youth tournament. He finished as the competition's top scorer and helped his team become the champions.
Following his promising performances in Croatia, Sadiq was acquired by Italian club Spezia. He failed to make any first-team appearances, but played regularly for the youth setup. In the 2014–15 season, Sadiq became the Campionato Primavera top scorer, tallying an impressive 26 goals in 24 games.
In July 2015, Sadiq joined Roma on a one-year loan. He was transferred alongside his teammate and compatriot Nura Abdullahi for €250,000 each with a buyout clause of €1,250 million per player. Having bagged eight goals in his first three Primavera matches for Roma, Sadiq made his Serie A debut on 21 November, replacing Juan Iturbe after 88 minutes in a 2–2 away draw against Bologna. He scored his first goal on 20 December, netting only seven minutes after coming on as an 82nd-minute substitute for Mohamed Salah, helping his team to a 2–0 home win over Genoa. On 6 January 2016, Sadiq bagged his second goal in his first start for Roma, opening the scoring in the 7th minute of an eventual 3–3 away draw against Chievo. He finished the season with two goals in six Serie A appearances.
On 31 August 2016, Sadiq was sent on loan to Bologna until the end of the season with a purchase option. He appeared in seven Serie A games, before returning to Roma.
On 16 August 2017, it was announced that Sadiq would be joining Torino on loan until 30 June 2018. The deal included an option to make the move permanent with a buyback clause in favour of Roma.
In January 2018, Sadiq moved on a six-month loan to Dutch side NAC Breda with an extension option. He helped the club narrowly avoid relegation, contributing with five goals in 12 Eredivisie appearances.
In July 2018, Sadiq joined Scottish Premiership side Rangers on a season-long loan. After just four first-team appearances in all competitions, his loan spell was terminated by the end of the year.
In January 2019, Sadiq joined Serie B side Perugia for the remainder of the season. He scored three times in 17 appearances, helping his team to an eight-place finish with a chance to win promotion to Serie A via the playoffs. However, Perugia lost in the preliminary round to Veronaafter extra time.
Loan to Partizan
In early July 2019, Sadiq completed his loan move to Serbian club Partizan that included an option to buy. He made his official debut in a 1–0 away league win against Inđija on 21 July. On 4 August, Sadiq netted his first goal for the club in a 4–0 home league victory over Mačva Šabac. He subsequently scored the opener in an eventual 3–1 home win versus Turkish club Yeni Malatyaspor in the first leg of the Europa League third qualifying round. On 3 October, Sadiq netted a brace to give his team a 2–1 away victory against Astana in Europa League's Group L. He scored his first senior hat-trick in a 6–2 home league win over Javor Ivanjica on 22 November.
International career
In July 2016, Sadiq was named in Nigeria's final 18-man squad for the 2016 Summer Olympics. He appeared in all six of his team's games and scored four goals in the process, including a brace in the third-place victory over Honduras.
