‘Tamcot G11' upland cotton (Gossypium hirsutum L.) cultivar (Reg. No. CV-135, PI 682743) was developed by Texas A&M AgriLife Research and released in 2017 as part of an ongoing effort to create cultivars and germplasm with combinations of improved fiber quality parameters, especially upper half mean length (UHML) and fiber bundle strength. Tamcot G11 is a conventional cultivar that is competitive in lint yield potential with current upland cultivars available for production in central and south Texas. Tamcot G11 exhibited significantly longer UHML, measured by high volume instrument (HVI), than the average of all comparison cultivars in 16 of 17 performance trials across central and south Texas during 2013 through 2016. Micronaire of Tamcot G11 was within the premium range in 12 of the 17 performance trials, while the control cultivars averaged the premium range in only 3 or the 17 trials. Strength of Tamcot G11 and the mean of all controls were equal in all except two trials, whereas Tamcot G11 tended to have lower fiber elongation at break. Lint yield of Tamcot G11 was equal to or greater than the average of all control cultivars in 16 of the 17 trials. Lint percentage of Tamcot G11 was acceptable yet below that of most current upland cultivars. Tamcot G11 provides producers with a competitive, high-quality conventional cultivar with UHML sufficient to reduce the probability of discounts based on fiber length.