As a pivotal group in the early evolution of metazoans, cnidarians serve as an ideal model for exploring the developmental and genetic mechanisms of early multicellular animals through the settlement and metamorphosis of their planula. In this study, the representative cnidarian species, Aurelia coerulea, was used to construct transcriptomic profiles of unattached and attached planula. RT-qPCR and pharmacological inhibition experiments were further performed to validate key regulatory pathways. The results showed substantial changes in gene expression patterns before and after planula attachment. Functional enrichment analysis revealed that genes in the attached stage were significantly enriched in developmental signaling pathways, cell surface receptor signaling pathways, and transcription factor activity, whereas genes in the unattached stage were mainly enriched in potassium ion channel activity, potassium ion transmembrane transport, and sodium ion channel activity. Gene expression analysis demonstrated that genes related to Wnt signaling were significantly upregulated at the attachment stage. Inhibition of the Wnt signaling pathway significantly reduced planula attachment rates and suppressed metamorphosis, indicating that Wnt signaling is involved in regulating the settlement and metamorphosis of A. coerulea planula. Overall, this study provides transcriptomic landscapes of critical stages during the settlement and metamorphosis of A. coerulea planula, preliminarily reveals the transcriptional regulatory characteristics underlying the process, and offers insights into the molecular regulatory mechanisms controlling planula settlement and metamorphosis in marine invertebrates.