Kylen /ky-len/ [2 sylls.] as a boys' name (also used less widely as girls' name Kylen) is of Gaelic origin, and the name Kylen means narrow, straight. Kylen is an alternate form of Kyle (Gaelic). Kuylen is a familiar last name.rominent related forms of Kylen (#984 last year) ranked in the Top 1000 are Kylan (#661 last year) , Kyle (#178) and Kyler (#288) . Variants like Kylar are seldom used. These boy names were at the top of their popularity in 2011 (usage of 0.4958%) and are almost as popular today (usage 0.4723%, down 4.7%).