MXenes suffer from rapid structural degradation in water, hindering long-term shelf-storage and applications. Current anti-degradation methods either require harsh storage conditions or complex surface treatment, resulting in high costs and intrinsic properties damage. Herein, we propose a versatile (low-cost, intrinsically preserved, high-dispersion, and open-ended) method that enables long-term shelf-storage and operation stability of MXenes by adding ethylene glycol (EG) into MXenes aqueous solution. EG-H2O hydrogen bonding limits water activity and decreases free water ratio, thereby inhibiting their attack on transitional metal atoms on MXene nanosheet surfaces leading to decelerate their degradation, as revealed by molecular dynamics simulations. The limiting-water-activity strategy derived from EG-H2O solvents extended shelf-life of MXenes dispersions over 6 times longer than that of pure water, and notably showed the versatility stabilizing MXenes in the range from Ti3C2Tx to Ti2CTx, Ti3CNTx, and V2CTx, where ~90% EG can be recycled. The versatile limiting-water-activity strategy additionally enabled long-term operation of MXenes in water-based devices: an EG-H2O-processed Ti3C2Tx MXene hydrogels sensor retained up to 95.2% sensitivity over 2-month cycling. This work provides a facile route for long-term shelf-storage and reliable operation of MXenes in water.