Electrolyte-gated transistors (EGTs) have attracted considerable interest due to their low-voltage operation and compatibility with soft and flexible electronic platforms. Here, we report a vertical EGT architecture that reduces the effective channel length to the submicron scale, resulting in enhanced on-current and transconductance. In parallel, ambipolar organic semiconductors offer a promising route to simplified device fabrication and circuit integration by enabling both hole and electron transport within a single material. However, practical ambipolar logic remains challenging because balanced carrier injection and stable switching are difficult to achieve. In this work, we demonstrate vertical ambipolar EGTs based on a single high-performance ambipolar organic semiconductor. The ambipolar electrochemical operation enables complementary logic functionality using one semiconducting material, providing a simple and scalable pathway toward integrated organic logic circuits.