Connectorized nano-engineered optical fibers and method for forming them are disclosed. The methods include heating a mid-span bare fiber portion of the nano-engineered fiber to collapse the airlines therein so as to form an airline-free portion. The fiber is then inserted into a ferrule channel so that the fiber end protrudes beyond the ferrule end face, but with the airline-free portion positioned at the ferrule end face. The fiber is then cleaved at or near the ferrule end face in the airline-free portion, and the new fiber end face polished to create a solid fiber end face that coincides with the ferrule end face. The methods result in at most only minimal changes to the mode field diameter (MFD) and/or to the outer cladding diameter, which is essential in forming a connectorized nano-engineered fiber that can connect to like-size nano-engineered or non-nano-engineered fibers.