Marine shellfish and finfish are common vectors of biotoxins produced by bacteria, cyanobacteria, and microalgae, severely affecting public health worldwide. Monitoring the presence of toxigenic microorganisms in the water and toxic compounds in seafood can be effective in preventing/mitigating intoxication outbreaks, although the risks are still high for emerging, underregulated toxins and/or in places where toxin monitoring is deficient. This paper summarizes the latest findings on seafood contamination by marine biotoxins including emerging toxic compounds, and presents the recent advances on analytical methods for toxin detection and regulation. Ultimately, the importance of adopting advanced techniques and an integrated notification system for mitigating the impacts of toxin contamination on human health worldwide is discussed, using Brazil as a case study.