Background Therapeutic options are limited for unresectable isolated recurrent cervical lymph node (LN). There are different methods of salvaging the recurrent nodes such as surgery, reirradiation by fractionated external beam radiation therapy, stereotactic body radiotherapy, and interstitial brachytherapy. However, interstitial brachytherapy method is very less commonly used. We highlighted a treated case of oropharyngeal cancer with isolated recurrent neck node treated with interstitial brachytherapy under ultrasound guidance. Methods and materials One 60-year-old male patient diagnosed with case of squamous cell carcinoma vallecula with left level II LN, cT2N1M0, was given 70 Gy in conventional fractionation to the gross primary and node and 59 Gy and 56 Gy to the intermediate and low-risk volumes, respectively. Post chemoradiation, we achieved complete metabolic and morphological response of the primary and neck node as well. However, he developed a recurrent fluorodeoxyglucose avid level II LN of size 3×2 cm after 7 months which was fixed. Positron emission tomography (PET) scan showed a PET avid recurrent node abutting the great vessels in the left side. We treated by computed tomography (CT)-based high-dose-rate interstitial brachytherapy using Ir-192. High-risk clinical target volume was defined as 1.5 cm margin around the gross tumor volume, trying to achieve 100% volume with 95% dose prescribing 35 Gy/10 fractions @ 350cGy/# to HRCTV using Oncentra treatment planning system. Result He developed complete metabolic response after 3 month of nodal brachytherapy confirmed by PET CT and remained disease free for 30 months till the last follow-up. Conclusion Ultrasonography-guided interstitial nodal brachytherapy is a valid option and feasible in previously irradiated patients with isolated recurrent neck node of head and neck cancers. However, more number of patients needed to be done by similar fashion for adequate data generation and proper conclusion.