This species as described appears to be a conglomeration of many distinct forms; three of these are currently recognized subspecies (ssp. lineata, ssp. bombetokensis, and ssp. punctulata), but others could be separate taxa that should be elevated to species status as was Phelsuma dorsivittata. Phelsuma lineata is not threatened, but some unknown subspecies might be.
The lined day gecko has soft, green skin on its back and a distinct black band running down the side of its body, bordered on the lower edge by a light-coloured stripe. It commonly measures between 10 and 14.5 cm in length.