While it would probably work, it might also shorten the life of the boots. Depending on how hard you are on shoes, this may be irrelevant as you could wear them out before long term damage occurs. However, you have to remember that leather (once living skin) has pores and needs to breathe. Instead of a hard surface sealant, invest in a quality leather protectant that will waterproof and care for the leather at the same time.