A novel Doherty-to-balanced (D2B) switchable power amplifiers (PAs) architecture based on branch-line quadrature hybrid couplers is presented. It is for the first time unveiled that by switching the 50-Ω loading at isolation port to a short circuit to ground, the balanced amplifier can be fully converted to a Doherty PA. The proof of the concept is demonstrated using a commercial SP2T SOI switch integrated with a balanced GaN power amplifier for mode reconfiguration. The implemented PA achieves efficient Doherty performance with a peak efficiency of 78.1% at maximum output power of 41.75 dBm, and 60.9% at 6 dB output power back-off (OBO). The balanced mode of this PA offers excellent immunity to load mismatch up to 5:1 VSWR achieving minimum output power fluctuation within 1 dB, as demonstrated experimentally.