Hayat will lead a 14-man squad to face Ireland and Scotland, and will be assisted by 23-year-old Aizaz Khan.
"I am honoured and extremely proud to be named captain of Hong Kong," Hayat said. "I must thank Tanwir for his efforts - the team has come a long way since he took over the captaincy and I'm sure I'll be using his experience on the field. We have some exciting new faces for the upcoming tour, which will be a test in Ireland and Scotland's home conditions."
Hayat, 24, made his international debut in March, 2014, in a World T20 game against Nepal, and has since played 20 T20Is in which he has scored 466 runs at 29.12 with one century. In seven ODIs, he has scored 184 runs at 26.28. In first-class cricket, he averages over 50.
"Babar thoroughly deserves this opportunity," Charlie Burke, HKCA's director of cricket, and selector, said. "His fitness and his determination to take this team and Hong Kong cricket forward really excites me. He has led from the front in training and shown he is ready for a leadership role."
Hong Kong's squad has two new faces - Ehsan Khan and Shahid Wasif. Hong Kong travel to Ireland first, where they take on the hosts in an Intercontinental-Cup clash in Belfast, before heading to Bready for two T20Is. Thereafter, they travel to Scotland for two ODIs.