Herein, a novel hydrogel, lignin/carbon dots-embedded cellulose nanofibrils hydrogel (LCCH), was fabricated for doxycycline (DOX) adsorption and determination. The adsorption characteristics of LCCH under various conditions were investigated. According to the Langmuir model fitting results, the maximum capacity of LCCH reached 1686mg/g. Moreover, it exhibited excellent reusability, with an adsorption capacity maintained above 80.4% after 5 cycles. Additionally, the LCCH demonstrated stable fluorescence properties, with DOX causing significant quenching of fluorescence attributed to both the internal filtration effect and static quenching. Within the ranges of 10–120mg/L and 0.2–1.0μg/L, the fluorescence of LCCH gradually decreased with the increasing concentration of DOX, reaching a limit of detection as low as 0.08μg/L. Lastly, a cost analysis considering energy consumption and reagent prices demonstrated LCCH's cost-effectiveness as an adsorbent. Overall, this study presents a novel approach for designing and preparing an effective, inexpensive, and versatile hydrogel for the removal of antibiotics.