Laser-based technologies have emerged as powerful tools for enhancing corrosion resistance and assessing sensitization in metals, particularly for stainless steels and 5xxx series aluminum (Al) alloys used in marine environments. A novel nanosecond laser surface processing technique significantly improved the pitting corrosion resistance of 304 stainless steel, achieving an optimal pitting potential of ~887 mV (from 503 mV) through the formation of gradient microstructures with ultrafine grains, dislocation accumulations, and coarse grains. For 5xxx Al alloys prone to sensitization and intergranular/stress corrosion cracking, a portable laser surface desensitization (LSD) system was developed for onboard ship use, reducing the degree of sensitization (DoS) of severely sensitized 5456 Al alloys from 46.8 mg/cm² to 1.7 mg/cm², while enhancing future sensitization resistance without compromising mechanical properties. Additionally, laser-induced breakdown spectroscopy (LIBS) combined with artificial intelligence was developed to assess DoS in 5xxx Al alloys, enabling accurate classification and prediction of sensitization levels by analyzing Mg concentration variations. These advanced laser-based approaches offer versatile, efficient, and portable solutions for corrosion remediation and material degradation assessment in critical marine applications.