The dual interrogation of the transcriptome and proteome with single-cell resolution provides exquisite insights into immune mechanisms in health and disease. Here, we describe a cutting-edge protocol wherein we combine Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-Seq), a technique utilizing antibody-oligonucleotide conjugates (AOCs), with fluorescence-activated cell sorting to enrich rare cell populations. Our protocol incorporates co-staining of cells with both fluorescent antibodies and AOCs simultaneously for subsequent input into the cell sorting and CITE-Seq pipeline. For complete details on the use and execution of this protocol, please refer to Mair et al. (2020). Keywords: Antibody; Biotechnology and bioengineering; Cell isolation; Flow Cytometry/Mass Cytometry; Immunology; Molecular Biology; Single Cell.