Real-time in vivo detection of different bioanalyte and biomarkers, particularly nitric oxide (NO) and temperature, is of utmost importance for critical healthcare monitoring, therapeutic dosing, and fundamental understanding of their role in regulating many physiological processes. However, the detection of NO in a biological medium is challenging due to its short lifetime and low concentration. Traditional methods of detecting bioanalyte and biomarkers suffer from many limitations such as complex sample preparation, complicated and expensive instrumentation, electromagnetic interference, etc. Here, we demonstrate for the first time that photonic Micro Ring Resonators (MRRs) can provide real-time, direct, and in vivo detection of NO in a mouse wound model. The MRR encodes the NO concentration information into its transfer function in the form of a resonance wavelength shift. We show that these functionalized MRRs, fabricated using CMOS-compatible processes, can achieve sensitive detection of NO (sub-µM) with excellent specificity, and no apparent performance degradation over more than 24 hours of operation in the biological medium. In another study, we show that this MRR can measure magnetic nanoparticle heating with high precision and fast temporal resolution (10 µs). MRR has negligible thermal mass and is not affected by electromagnetic interference; therefore, it can provide a more accurate measurement of specific absorption rate for sample volume as small as a few µL. We also demonstrate that MRR can measure the temperature gradient of a sample substrate with high spatial resolution and is capable of measuring the multiplexing capability of dual-channel magnetic nanoparticles. Finally, we could successfully measure the temperature of the targeted region of the brain slice during AMF stimulation which is not possible with traditional methods. Therefore, with alternative functionalization, this compact lab-on-chip optical sensing platform could support the real-time detection of myriad biochemical species and biomarkers and can revolutionize the field of biomedical science and healthcare monitoring.