The effects of Li2O–ZnO–B2O3 (LZB) glass addition on densification and dielectric properties of Ba4(Nd0.85Bi0.15)9.33Ti18O54 (BNBT) have been investigated. At a given ratio of ZnO/B2O3, the glass softening point decreases, but the thermal expansion coefficient and dielectric constant increase with increasing Li2O content in the LZB glass. With 10 vol% LZB glass, the densification temperature reduces greatly from 1300°C for pure BNBT to 875°C–900°C for BNBT + LZB dielectric, and the densification enhancement becomes more significant with increasing Li2O content in the LZB glass. The above result is attributed to a chemical reaction taking place at the interface of LZB/BNBT during firing, which becomes less extensive with increasing Li2O content in the LZB glass. Therefore, more residual LZB glass, which acts as a densification promoter to BNBT, is left with increasing Li2O content. For the LZB glass with a Li2O content in the range 10–30 mol%, the resulting 90 vol% BNBT + 10 vol% LZB microwave dielectric has a dielectric constant of 55–70, product (Q × fr) of quality factor (Q) and resonant frequency (fr) of 1000–3000 GHz at 5–5.79 GHz, and a temperature coefficient of resonant frequency (τf) of 10–60 ppm/°C in the temperature range between 25°C and 80°C.