Completion of the site is expected in time for the 2016/17 academic year and will provide a home for 399 students.
The Causewayend scheme is expected to have a development cost of £20m.
The site is being acquired from Aberdeen City Council and is currently occupied by a derelict, listed school building.
The site is situated in the centre of Aberdeen close to Unite’s existing investment portfolio near to the University of Aberdeen with good transport links to Robert Gordon University.
Richard Simpson, Managing Director of Property for Unite Students, said: “We are very pleased to have received planning consent for this site as our development pipeline continues to progress well.
“This is our fifth site in Aberdeen, where we already provide a home for over 1,300 students.
“Causewayend will provide a safe and secure home for students and will help to strengthen our relationships with University of Aberdeen and Robert Gordon University and meet the accommodation demands of Aberdeen’s growing student population, whilst contributing to the regeneration of the area.”