The purpose of this chapter is to explore the use of mobile devices (i.e., smartphones, smartwatches, tablets) by Generation Y (Millennials), in the three phases of travel (pre-trip, on-site, post-trip). In order to meet this purpose, a survey was conducted via a structured self-completed questionnaire in a sample of 211 Millennials in Greece. The study's results revealed that Millennials are heavy users of the internet and social media to which they connect daily and spend several hours of the day. Mobile devices are used by Millennials during all three phases of a trip (pre-trip, on-site, and post-trip), however, to different extents and for different purposes. Further, this research showed that Millennials have downloaded many different types of travel-related applications. Special mention is also made of the advantages of mobile devices for travel purposes in the COVID-19 era.