In anticipation of abundant B⁎ data samples at high-luminosity heavy-flavor experiments in the future, the tree-dominated semileptonic B¯u,d,s⁎→Pℓ−ν¯ℓ (P=D,Ds,π,K) decays are studied within the Standard Model. After a detailed calculation of the helicity amplitudes, the theoretical predictions for branching fraction (decay rate), lepton spin asymmetry, forward–backward asymmetry and ratio RD⁎(L) are firstly presented. It is found that the CKM-favored B¯⁎→Dℓ−ν¯ℓ decays have relatively large branching fractions of O(10−9)∼O(10−7), and are in the scope of running LHC and forthcoming SuperKEKB/Belle-II experiments.