Electric dipole transition probabilities and oscillator strengths for singly ionized terbium (Tb II) have been calculated with the weakest bound electron potential model (WBEPM) theory using experimental energy levels and theoretical expectation values of orbital radii corresponding to those energy levels under the assumption of the Jj coupling scheme. The transition probabilities and the oscillator strengths calculated have been compared with available data in the literature. A good agreement has been obtained. In this work, the WBEPM theory has been applied to heavy atoms, such as Tb II, for the first time. © 2014 Published by NRC Research Press.