This study investigated the diversity and carriage rate of nasalStaphylococcusspp., and within-host variability of antimicrobial resistance (AMR), virulence determinants, immune evasion cluster (IEC) types and genetic lineages ofS. aureusisolates. Also, the co-carriage rate of CoNS withS. aureusin the same nasal niche of healthy pigs and pig-farmers were studied in four pig-farms (A-D) in Aragon (Spain). Nasal samples of 40 pigs (10 pigs/farm) and 10 pig-farmers (2–3/farm) were collected for staphylococci recovery and isolates (up to 9 per sample) were identified by MALDI-TOF-MS. The virulence and AMR genes andspa-types ofS. aureusisolates were investigated by PCR/sequencing. Of the 243 staphylococci identified (10 different species), 142 wereS. aureusand 51 distinct isolates were selected for further characterization (that corresponded to oneS. aureus/sample or more than one if they showed different AMR phenotypes). The highest carriage rate in pigs wasS. aureus(65%) andS. chromogenes(22.5%), whereas in the pig-farmers,S. aureus(80%) andS. epidermidis(40%). Methicillin-resistantS. aureus(MRSA) were detected in 60% of pigs and 70% of pig-farmers. Only sixS. aureusisolates were methicillin-susceptible (MSSA), all from farm-C. A multidrug resistance (MDR) phenotype was detected in all MRSA and in 83.3% of the MSSA isolates. All MRSA isolates were CC398 withspa-type t011 being the predominant (92.7%), while t034, t1451 (only in pig-farmers) and t4571 (in pigs) were also found. MSSA-CC9 isolates (t191, t1430) were detected in farm-C. AllS. aureusisolates were negative forluk-S/F-PV, tst,andscngenes, except one MSSA-CC45-t065-IEC-type C isolate from a pig-farmer. About 34.6% and 75.0% of the pigs and pig-farmersS. aureuscarriers, respectively, harboured within-host variedspa-types or resistomes. Moreover, 40% of pigs and pig-farmers with MRSA-CC398 had no CoNS nasal co-carriage, and 23.3% had ≥2 CoNS carriage. Conversely, only 16.7% of MSSA carriers had no CoNS co-carriage, whereas 50% had ≥2 CoNS carriages. The very high MRSA level and within-host resistome diversities highlight the need for multiple samplings to account for the dynamics of AMR crisis and control of inter-host transmission ofS. aureusin pig-farms using “One Health” approach.