This paper presents a systematic diagnostic approach towards the characterization of herbicide resistance in a given weed population with regards to profile (single, multiple, cross resistance), magnitude (fold level), mechanism, and related bio-physiological aspects. Diagnosing herbicide-resistant weeds can be achieved by crafting robust procedures for seed sampling, survey protocol and seed collection, seed processing and storage, germination, emergence and growth (sufficient number of representative plants), treatment conditions (i.e., discriminating dose, adjuvants, spray volume and parameters, water quality, and nutrient status), experimental design, appropriate controls including wild type/susceptible accessions, and biological parameters being measured. Understanding the processes and means by which weeds withstand labeled herbicide treatments is an important step, as well, towards devising effective herbicide resistance management strategies. Several physiological, biochemical, and molecular approaches for studying resistance mechanisms are available to researchers. The various omics approaches including genomics (DNA), transcriptomics (RNA), proteomics (proteins), and metabolomics (metabolites) will revolutionize herbicide resistance research.