We report a process to assemble carbon nanotubes (CNTs) into patterned and periodic structures by self‐assembly at room temperature. Patterns of 10 μm or smaller can be readily deposited on various types of substrates using functionalized CNTs. The self‐assembled CNTs have in‐plane orientational order, and adhere strongly to the substrates. Under applied electric field they emit electrons with emission characteristics comparable to the CNT cathodes made by other techniques. This room temperature process can be utilized for assembly and integration of nano‐structured materials for a variety of devices including field emission displays.