  We utilize a sample of 34.6 fb$^{-1}$, collected by the Belle II experiment
at the SuperKEKB asymmetric energy $e^+e^-$ collider, to search for the $B^+
\to \phi K^+$, $B^+ \to \phi K^{*+}$, $B^0 \to \phi K^0_S$, and $B^0 \to \phi
K^{*0}$ decays. Charmless hadronic $B$ decays represent an important part of
the Belle II physics program, and are an ideal benchmark to test the detector
capabilities in terms of tracking efficiency, charged particle identification,
vertexing, and advanced analysis techniques. Each channel is observed with a
significance that exceeds 5 standard deviations, and we obtain measurements of
their branching ratios that are in good agreement with the world averages. For
the $B \to \phi K^*$ modes, we also perform a measurement of the longitudinal
polarization fraction $f_L$.
