© 2021 World Scientific Publishing Company.In this paper, we examine massless scalar field by using unimodular f(R) theory. It is taken into account unimodular and cylindrically symmetric spacetime which provides convenience in researching black hole. The field equations in unimodular f(R) theory for given spacetime with massless scalar field and additional Bianchi identities are solved. Cylindrically symmetric anti-de Sitter (AdS)-Schwarzschild-like and AdS-Reissner-Nordström-like black hole spacetimes are achieved. Equations of motion are derived by using Hamiltonian. Orbits of massless test particles are depicted. Obtained line element asymptotically converges to dS/AdS spacetime. Weak and strong energy conditions of the massless scalar field are obtained with Raychaudhuri equations in unimodular f(R) theory. Also, stiff fluid interpretation of scalar field is reviewed.