In the present research, the wettability of boron carbide ceramic by BNi-1 filler alloy at various contact times from 10 to 40 min has been studied. The results of sessile drop wetting tests showed that the BNi-1 filler alloy could spread well on the B4C surface at 10–40 min. With the increase of the contact time from the lowest time (10 min) to the highest time (40 min), the contact angle stably reduced, showing the enhancement of the spreading. However, by the increase of the contact time from 30 to 40 min, a slight change was observed in the wetting angle (from 21° to 19°). Overall, the appropriate spreading behavior of BNi-1 filler alloy on the B4C substrate can be attributed to the tendency of nickel for the reaction with B4C along with the simultaneous availability of silicon and chromium in the composition of this alloy. The maximum wetting angle of 48° was attained for the specimen with 10 min contact time and the minimum angle of 19° was achieved for the specimen with 40 min contact time. Due to the results, different compounds such as Ni4B3, CrB2, CrB, SiC, and Ni2Si have been observed at the system's interface. Moreover, the higher contact times can lead to the intensification of the system's interactions which can subsequently result in the higher penetration of the elements, the reacted area enlargement, and the formation of diverse microstructures and phases. The wetting experiments' results confirmed the spreading ratio calculations.