Mass spectrometry performed in non-denaturing conditions (native MS), and its hyphenation to ion mobility spectrometry (IM-MS), have gained interest for the qualitative and quantitative characterization of intact monoclonal antibody-related (mAb) products. However, one main drawback is the manual sample preparation, which hampers its routine use in high throughput automated environments. Size exclusion chromatography (SEC) appears as an interesting technique to perform online buffer exchange in an automated way. We present here an exhaustive and systematic evaluation of the possibilities and versatility of SEC direct hyphenation to native MS or IM-MS (SEC-nativeMS/IM-MS) for the characterization of a variety of mAb-formats (IgGs, ADCs,bispecific mAbs and Fc-fusion proteins). First, online SEC-native MS allows automated sample preparation, resulting in high resolution mass spectra and improved mass accuracies (< 80 ppm) compared to manual buffer exchange procedures. When hyphenated to ion mobility, SEC-native IM-MS can deliver conformational characterization through collision cross section (CCS) measurements within few minutes without affecting mAb structures. Finally, benefits of online SEC-nativeIM-MS compared to standalone SEC-UV or native MS techniques are demonstrated for higher order structure characterization of mAb forced degraded samples. While SEC provides separation of high/low molecular weight species from the main mAb peak along with precise quantification of the species, native MS affords complementary unambiguous identification of SEC peaks, even when poor SEC separation is achieved. The synergic online coupling of SEC to native MS/IM-MS is envisioned to definitely push native MS approaches at the forefront of mAb characterization in quality-controlled environments and as multiple monitoring method.