Metal halide perovskites have shown outstanding optoelectronic and nonlinear optical properties; yet, to realize wafer-scale high-performance perovskite-integrated photonics, the materials also need to have excellent ambient stability and compatibility with nanofabrication processes. In this work, we introduce Dion-Jacobson (D-J) phase perovskites for photonic device applications. By combining self-assembled monolayer-assisted film growth with thermal pressing, we obtain a series of compact and extremely smooth D-J phase perovskite thin films that exhibit excellent stability during electron-beam lithography, solvent development, and rinse. Combining spectroscopic and morphological characterizations, we further demonstrate how organic spacers can be used to fine-tune the photophysical properties and processability of the perovskite films. The distributed-feedback lasers based on the D-J phase perovskites exhibit a low lasing threshold (5.5 μJ cm-2 pumped with nanosecond laser), record high Q factor (up to 30,000), and excellent stability, with an unencapsulated device demonstrating a T90 beyond 60 hours in ambient conditions (50% relative humidity).