Organoboron compounds and their derivatives are synthetically versatile building blocks because of their readily availability, stability, and variety of functional groups tolerance.[1] Among them, a well-established method to afford arylboronic esters is transition metal catalyzed borylations of aryl halides. However, the use of aryl halides as an electrophile has some disadvantages such as formation of toxic halogenated byproducts. Recently, the use of C(sp2)–O electrophiles has turned out to be a promising alternative to aryl halide such as aryl esters, carbamates and sulfonates.[2] However, the aryl methyl ether, which is one of the simplest phenol derivatives, remains as a challenge, as C–OMe bond activation requires high activation energy and methoxides are not generally good leaving groups. Thus, only one example of ipso-borylation of aryl methyl ether has been demonstrated by Martin’s nickel catalysis in 2015.[3] Here, we present cotalt-catalyzed unactivated C–OMe bond borylation. Not only C(sp2)–OMe bond but also C(sp3)–OMe bond could be borylated under our condition. This reaction can be set up under aerobic condition and also does not require a presynthesized organometallic complex. A mild and practical Co-catalyzed borylation of various substrates enables a new reaction strategy in synthetic chemistry. Reference [1] Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457-2483. [2] Cornella, J.; Zarate, C.; Martin, R. Chem. Soc. Rev. 2014, 43, 8081-8097. [3] Zarate, C. ; Manzano, R.; Martin, R. J. Am. Chem. Soc. 2015, 137, 6754-6757.