The “deep” proteome has been accessible by mass spectrometry for some time. However, the number of proteins identified in cells of the same type has plateaued at ~8,000-10,000 without ID transfer from reference proteomes/data. Moreover, limited sequence coverage hampers the discrimination of protein isoforms when using trypsin as standard protease. Multi-enzyme approaches appear to improve sequence coverage and subsequent isoform discrimination. Here, we expanded proteome and protein sequence coverage in MCF-7 breast cancer cells to an as yet unmatched depth, by employing a workflow that addresses current limitations in deep proteome analysis at multiple stages: We used i) Gel-aided sample preparation (GASP) and combined trypsin/elastase digests to increase peptide orthogonality, ii) concatenated high pH pre-fractionation and iii) CHarge Ordered Parallel Ion aNalysis (CHOPIN)- available on an Orbitrap Fusion (Lumos) mass spectrometer- to achieve 57% median protein sequence coverage in 13,728 protein groups (8,949 Unigene IDs) in a single cell line. CHOPIN allows the use of both detectors in the Orbitrap on predefined precursor types that optimizes parallel ion processing, leading to the identification of a total of 179,549 unique peptides covering the deep proteome in unprecedented detail.