Pegfilgrastim is administered as an adjunct to chemotherapy to reduce the incidence of febrile neutropenia and associated infectious complications. Lupin's Pegfilgrastim is a proposed biosimilar to the U.S.-referenced Neulasta®. Demonstration of biosimilarity requires extensive physicochemical and functional characterization of the biosimilar, and demonstration of analytical similarity to the reference product, in addition to clinical studies. This work is a case study for demonstrating the analytical similarity of Armlupeg (Lupin's Pegfilgrastim) to Neulasta® with respect to structural and physicochemical attributes using several robust, orthogonal, and state-of-the-art techniques including high-end liquid chromatography, mass spectrometry, and spectroscopy techniques; circular dichroism; differential scanning calorimetry; nuclear magnetic resonance; analytical ultracentrifugation; and micro-flow imaging. Functional similarity was demonstrated using an in vitro cell proliferation assay to measure relative potency and surface plasmon resonance to measure receptor binding kinetics. Furthermore, comparative forced-degradation studies were performed to study the degradation of the products under stress conditions. The product attributes were ranked based on a critical quality attributes risk score according to their potential clinical impact. Based on criticality, all analyses were statistically evaluated to conclude analytical similarity. Lupin's Pegfilgrastim was comparable to Neulasta® as demonstrated via structural, functional, and purity analyses. Lupin's Pegfilgrastim complied with the quality and statistical ranges established using Neulasta®. Both products follow the same degradation pathways under stress conditions as observed in the forced-degradation studies. No new impurity or degradation product was observed in Lupin's Pegfilgrastim. These data conclusively demonstrate the analytical similarity of Lupin's Pegfilgrastim and Neulasta®.