Should I use footnotes to cite sources in MLA style?

No, you should use parenthetical MLA in-text citations to cite sources. Footnotes or endnotes can be used to add extra information that doesn’t fit into your main text, but they’re not needed for citations.

If you need to cite a lot of sources at the same point in the text, though, placing these citations in a note can be a good way to avoid cluttering your text.