In vivo fluorescence imaging in the second nearinfrared window (NIR-II) affords deep-tissue penetration and high spatial resolution. Herein, we present anew type of Tm 3+sensitized lanthanide nanocrystals with both excitation (1208 nm) and emission (1525 nm) located in the NIR-II window for in vivo optical information storage and decoding. Taking advantage of the tunable fluorescence lifetimes,t he optical multiplexed encoding capacity is enhanced accordingly. Micro-devices with QR codes featuring the NIR-II fluorescence-lifetime multiplexed encoding were implanted into mice and were successfully decoded through time-gated fluorescence imaging technology.