Inspired by the ability of SERS nanoantennas to provide an integrated platform to enhance disease targeting in vivo, we developed a highly sensitive probe for in vivo tumoral recognition with the capacity to target specific cancer biomarkers such as epidermal growth factor receptors (EGFR) on human cancer cells and xenograft tumour models. Here, we used ~90 nm gold nanoparticles capped by a Raman reporter, encapsulated and entrapped by larger polymers and a FDA antibody-drug conjugate –Cetuximab (Erbitux®) – that specifically targets EGFR and turns off a main signalling cascade for cancer cells to proliferate and survive. These drug/SERS gold nanoantennas present a high Raman signal both in cancer cells and in mice bearing xenograft tumours. Moreover, the Raman detection signal is accomplished simultaneously by extensive tumour growth inhibition in mice, making these gold nanoantennas ideal for cancer nanotheranostics, i.e. tumour detection and tumoral cell inhibition at the same time