This paper presents the fabrication, characterization and numerical simulation of poly-3-hexylthiophene (P3HT)-based bottom-gate bottom-contact (BGBC) organic thin film transistors (OTFTs). The simulation is based on a drift diffusion charge transport model and density of defect states (DOS) for the traps in the band gap of the P3HT based channel. It combines two mobility models, a hopping mobility model and the Poole–Frenkel mobility model. It also describes the defect density of states (DOS) for both tail and deep states. The model takes into account all the operating regions of the OTFT and includes sub-threshold and above threshold characteristics of OTFTs. The model has been verified by comparing the numerically simulated results with the experimental results. This model is also used to simulate different structure in four configurations of OTFT e.g. bottom-gate bottom-contact (BGBC), bottom-gate top-contact (BGTC), top-gate bottom-contact (TGBC) and top-gate top-contact (TGTC) configurations of the OTFTs. We also present the compact modeling and model parameter extraction of the P3HT-based OTFTs. The extracted compact model has been further applied in a p-channel OTFT-based inverter and three stage ring oscillator circuit simulation.