Yes, someone can put a lien on your house without your knowledge, though it’s not common. Liens are typically placed on a property after a legal process, such as a lawsuit or a judgment. Depending on how your county or state notifies of liens, you may not be aware of those that exist on your property. However, if you haven’t paid a debt, you likely know about it and the lien shouldn’t be a surprise if too much time has passed.