Two solvatochromic fluorenone-tetraphenylethene luminogens, 2-(4-(1,2,2-triphenylvinyl)phenyl)-9H-fluoren-9-one (TPE-FO) and 2,7-bis(4-(1,2,2-triphenylvinyl)phenyl)-9H-fluoren-9-one (TPE-FO-TPE), have been designed and synthesized, in which tetraphenylethene offers dual functions, i.e., aggregation-induced emission (AIE) and electron donation. Both TPE-FO and TPE-FO-TPE exhibit pronounced solvatochromic effects and AIEE activity. The two luminogens exhibit ultra-high sensitivity to trace water in organic solvents such as THF or dioxane. The Stern–Volmer plots show good linear relationships with water fractions below 0.9%. The detection limit of TPE-FO for water in THF is calculated to be 11 ppm which is pretty close to that of Karl–Fischer titration.