Varila's research focuses on late medieval and early modern English text and book production. She is interested in the linguistic, textual, material and visual practices of scribes, printers, and compilers. She approaches this topic from a philological perspective, combining methods from historical discourse linguistics and book studies to study early texts in context.

Varila's PhD dissertation (2016) focuses on a group of three mid-sixteenth-century English scientific manuscripts. In it, she examines scribal practices and patterns of textual transmission in connection to scientific writing, taking into account codicological, palaeographical, textual, and linguistic evidence. Building on her findings regarding the interaction between manuscript and print in the sixteenth century, she has recently undertaken a new project in which she explores transmission of text from print to manuscript in early modern England. She also works as a postdoctoral researcher in the Early Modern Graphic Literacies project (PI Matti Peikola, funded by the Academy of Finland 2021-25), developing a model for classifying early printed graphic devices and investigating the use of graphic devices in early modern medical writing.

Varila has also published on scribal practices (2014), the interplay of textual and visual features (Carroll et al. 2013, Varila et al. 2017, Peikola & Varila 2023) and paratext in early English print (Varila 2018, Varila & Peikola 2019, Varila et al. 2020, Varila 2020). In addition to English materials, Varila has published on early modern manuscripts and printed books held by Turku City Library (Peikola & Varila 2017, 2015) and the Donner Institute at Åbo Akademi (Van Impe & Varila 2016).

Varila is currently a board member of the Finnish Society for Book History (2018-) and was previously a board member of the Finnish Society for the Study of English (2017-20). She also regularly participates in the activities of the local and national doctoral training networks Utuling and Langnet.