He has worked with various firms abroad and in Nigeria before setting up his own practice. They included Ove Arup and Partners (Nigeria), Osot Associates (Nigeria) De Leuw Cather (Canada) ND Lee and Associates (Canada) and Mclaren International (Canada and Nigeria). He was one of the founding Partners of Landscope Consultants, Ibadan, and later set up his own practice in 1980 when he established YOLAS CONSULTANTS with headquarters in Ilorin. He is the Chairman/CEO of Yolas Consultants with offices in Ilorin, Lagos and Abuja and has over 150 employees. The firm has executed many landmark projects in Nigeria and trained various categories of Engineers. In pursuit of his service to humanity, he established a school, Aderoju Sagaya Nursery and Primary School named after his late wife.
Engr. Sagaya has served Nigeria and Kwara State in various capacities. He was the Chairman of the Board of Trustees of the State Family Support Trust Fund. He has also served as a member of the Board of Trustees of Kwara State Industrial Development Fund. He was a member of Kwara State Scholarship Board, a former member of Nigerian Building and Road Research Institute Board and had also served as the Chairman of the Kwara State (Ilorin) chapter of the Nigerian Society of Engineers for two consecutive terms 1992 â€“ 1994 as well as the Chairman of Kwara State Town Planning and Development Authority between 1990 and 1994. Engr. Sagaya was honoured by the Emir of Ilorin in November 2006 with the Traditional Title of Zanna of Ilorin. He was honoured by Kwara State Government as a Prominent Citizen during the celebration of Nigeria at 50 in year 2010.
He is a COREN Registered Engineer, Past President of Association of Consulting Engineers of Nigeria (ACEN), Fellow, Nigeria Society of Engineers, Nigeria Institute of Structural Engineers (FNIStrutE), Nigeria Institution of Civil Engineers (FNICE), Member, Council of Registered Engineers of Nigeria (COREN). Engr. Sagaya was awarded the Nigerian National Honour as a Member of the Federal Republic (MFR) 2006, and Officer of the Order of the Federal Republic (OFR) in 2011.