In double-stranded DNA bacteriophage, the portal complex is a 12-subunit channel that constitutes part of the head-to-tail connecting interface. The portal is involved in capsid assembly and facilitates the passage of DNA during both genome packaging and infection. While portal structures have been well-characterised for several model phage, structural information on portals belonging to diverse and clinically relevant phage is still emerging. Finegoldia magna is a Gram-positive, anaerobic opportunistic human pathogen for which infecting phage have only recently been discovered. Here, we present the structure of the portal complex from the F. magna phage Miquella to a resolution of 2.8 Å using cryo-electron microscopy. The 2D class averages revealed C13-symmetric oligomers as the predominant assembly (95%), with a minor C12-symmetric population (5%), consistent with the oligomeric plasticity reported for other phage portals in solution. Monomers of the reconstructed 13-subunit assembly adopt the canonical crown, wing, stem, and clip domains. Comparison of the Miquella portal with the co-discovered F. magna phage Malenia portal reveals a high degree of structural conservation despite the two phage belonging to different families, with notable differences in the wing and clip regions. These findings offer insight into both conserved and divergent portal features. The Miquella portal structure obtained here serves as a basis for further comparative and functional studies and provides a framework for engineering portals for synthetic and therapeutic applications.