[3][4] Born in Labadi, Ghana and growing up in the capital city of Ghana,[5] Mensiro began playing football when he was six years old and after joining Right to Dream Academy and Sporting Club Accra, he moved out his parents’ house to pursue his opportunity.
[11] Shortly after the move, it was announced that Mensiro was given an all clear to play the club despite being on the student visa at the time.
[20] Despite missing one match, Mensiro helped the side reach promotion for the second time by winning the Division 1 Norra in the 2012 season, as he went on to make 26 appearances in all competitions.
"[7] Nevertheless, he continued to feature in the first team, but was soon sent–off for a foul on Modou Barrow, in a 3–1 loss against Varbergs BoIS on 18 May 2013.
[28] Mensiro made his Örebro SK debut in the opening game of the season, where he came on as a late substitute, in a 2–1 win over Halmstad.
[31] Although he returned from injury in August,[32] Mensiro remained out of the first team despite playing for the reserve side after his recovery.
[34] He appeared the remaining matches for the Svenska Cupen, including the final against IFK Göteborg, which saw them lose 2–1.
[40] However, Mensiro spent the first two months on the substitute bench, due to his continuous recovery from his knee injury and competitions from Saman Ghoddos, Ronald Mukiibi and Ken Sema.
[49] Shortly after his return, he quickly regained his first team place in number of matches, mostly playing in the centre–back and right–midfield position.
[51] Mensiro was part of the squad when he helped the side defeat the teams of Galatasaray,[52] Fola Esch,[53] and PAOK to secure the club's historic entry into the Europa League group stage.
[57] In the 2018 season, Mensiro started the whole game in the round of 32 first leg of the UEFA Europa League, in a 3–0 loss against Arsenal.
[58] Although he appeared as an unused substitute in a follow-up leg, which saw Ostersunds FK beat Arsenal 2–1 at the Emirates Stadium, they exited the competition after losing 4–2 on aggregate.
[59] However, Mensiro spent the start of the season on the sidelines, due to his own injury concern and was placed on the substitute bench instead.
[4][63] In June 2013, Mensiro was arrested on suspicion of rape, but was quickly released and was informed that no charges would be taken against him any further.