As an indispensable component in the photonic integrated circuits, the design and fabrication of optical isolators, particularly in the transverse electric (TE) polarized mode, is a long-standing challenge. Herein, we present a TE mode magneto-optical isolator using adiabatic tapered waveguides to realize conversions between designated modes. The isolator exhibits an ultranarrow structure of 1.27 μm × 1498 μm. We demonstrate that the device functions under a TE mode input with a maximum isolation ratio of 15 dB and an insertion loss of 5 dB at a wavelength of 1537.3 nm.