Celery is a biennial herb of the Apiaceae family and is a leafy vegetable crop widely cultivated worldwide. TCP (teosinte branched1/cycloidea/proliferating cell factors), a transcription factor family, is involved in cell growth and leaf tissue proliferation. In this study, 32 AgTCP transcription factors were identified and analyzed based on the celery transcriptome and genome database and divided into two classes. Analysis of structural feature, phylogenetic tree, interaction network, and subcellular localization of AgTCP proteins was performed. It is shown that the AgTCP2 protein was positioned in the nucleus, and TCP proteins in the same group had higher similarity. Heatmap clusters of AgTCP genes expression levels during different celery leaf developmental stages suggested that the genes from the same evolutionary branch tended to form a cluster. The expression profiles of four AgTCP genes were detected at celery leaf developmental stages and under gibberellin (GA3) treatment. As a CYC-type gene, AgTCP4 showed significantly increased expression levels under developmental stage and GA3 treatment in ‘Liuhe Huangxinqin’. The results of this work give potential helpful information for further analysis of the role of AgTCP transcription factors in leaf development and hormone regulation in celery.