Novel lettuce cultivar, designated GIMLET, is disclosed. The invention relates to the seeds of lettuce cultivar GIMLET, to the plants of lettuce line GIMLET, and to methods for producing a lettuce plant by crossing the cultivar GIMLET with itself or another lettuce line, respectively. The invention further relates to methods for producing a lettuce plant containing in its genetic material one or more transgenes and to the transgenic plants produced by that method and to methods for producing other lettuce lines derived from the cultivar GIMLET.