We report the discovery of the transiting extrasolar planet HAT-P-49b. The planet transits the bright (V=10.3) slightly evolved F-star HD340099 with a mass of 1.54M_{Sun} and a radius of 1.83R{Sun}. HAT-P-49b is orbiting one of the 25 brightest stars to host a transiting planet which makes this a favorable candidate for detailed follow-up. This system is an especially strong target for Rossiter-McLaughlin follow-up due to the host star's fast rotation, 16km/s. The planetary companion has a period of 2.6915 days, mass of 1.73M_J, and radius of 1.41R_J_. The planetary characteristics are consistent with that of a classical hot Jupiter but we note that this is the fourth most massive star to host a transiting planet with both M_p_ and R_p_ well determined.