Over the last 20 years, carbon nanotubes (CNTs) have developed as good candidates for various devices [1-6], electron •eld emission [7-9], composites [10-12], and sensors [13-15], because of their unique optical, electronic, and mechanical properties and their chemical stability [16-18]. Thereby they have attracted much interest from scientists in different research •elds. The Nobel laureate Richard Smalley said that carbon nanotubes would be cheap, environmentally friendly, and do wonders for humankind [19]. Almost at the same time carbon nanotubes were discovered, the simple and versatile layer-by-layer (LbL) technique was introduced for preparing thin polymer •lms [20,21]. This technique has also been widely used to greatly improve controlling over the surface properties of advanced materials with speci•c and tailored functions on the nanoscale. Various components can be used as building blocks in the LbL assembly, which has been performed on a wide range of substrate surfaces. Due to the unique properties of CNTs and versatile LbL technique, fabricating functional materials via introducing carbon nanotubes in LbL systems results in an ideal design. In fact, CNT-based LbL assembly has found application in diverse areas, ranging from biotechnology and biomedicine to nanoengineering.