A reliable and low-cost solution-processing procedure to synthesize a highly adhesive flexible metal antenna with low resistivity for radio-frequency identification device (RFID) tags on paper substrates via inkjet printing combined with surface modification and electroless deposition (ELD) is demonstrated in this paper. Through the surface modification of colloidal solution of hydrolyzed stannous chloride and chitosan solution, the paper-based substrate is able to reduce the penetration rate of ink and further increase the adsorption amount of silver ions, which could create a catalytic activating layer to catalyze the subsequent ELD of a conductive deposited metal antenna. The resulting metal antenna for RFID tags presents good adhesive strength and low resistivity of 2.58 × 10 −8 Ω·m after 40 min of ELD, and maintains a reliable reading range of RFID tags even after over 1000 times of bending and mechanical stress. Consequently, the developed technology proposed allows for cheap, efficient, and massive production of metal antenna for paper-based RFID tags with excellent mechanical and electrical properties. Furthermore, this process is especially advantageous for the fabrication of next-generation flexible electronic devices based on paper substrates.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201902579.identification technology in IOT. [2] Different kinds of substrates have been applied to fabricate RFID tags, including polyethylene terephthalate, [3][4][5] polyethylene naphthalate, [6][7][8] polyimide (PI), [9][10][11] and paper. [12,13] Paper is not only widely available, inexpensive, and well established but also lightweight, biodegradable, and can be creased for storage in small spaces or made into 3D self-standing structures; [14,15] so it is an ideal flexible substrate for RFID tags. Using paper as an insulating substrate, it is possible to fabricate RFID tags i) that do not need extra coarsening process because of enough surface roughness; [16] ii) that can naturally degrade; [17] iii) that is an abundantly available renewable material; [18] iv) that involves little absorption of electromagnetic energy due to its low dielectric constant and loss tangent angle. [19][20][21][22] Commercial paper-based RFID tags comprise metal antenna, integrated circuit (IC), and paper substrate, of which metal antenna accounts for 80% of the whole tag cost. [23] At present, the most mature method for preparing metal antenna RFID tag based on organic plastic substrate in industry is the subtractive etching method. [24] Although this traditional method of manufacturing metal antenna shows some superior characteristics, including high accuracy, low resistivity, and good weather resistance, it does generate some disadvantages such as high cost, restriction about substrate type, and environmental pollution. [20,25] In addition, the damage to fiber structure in paper substrate cannot be avoided due to the oxidation of fiber by the strong acid etching s...