Essential UNIX commands include 'ls' to list directory contents, 'cd' to change directories, 'pwd' to display the current working directory, 'cp' to copy files and directories, 'mv' to move or rename files and directories, 'rm' to remove files and directories, 'cat' to concatenate and display file contents, and 'chmod' to change file permissions. Becoming proficient with these commands is foundational for navigating and manipulating the file system in a UNIX environment.