Intra-articular (IA) administration of drugs is an appealing route for the effective treatment of large-joint diseases. However, a key limitation of this route is the premature elimination of the injected drugs from the synovial cavity. The objective of this work was to develop an easily injectable controlled release system intended to prolong the activity of anti-inflammatory drugs in the articular cavity. The system was an in situ forming hydrogel, made of fibrin and hyaluronic acid (HA), loaded with nanocapsules (NCs). The NCs, consisting of an olive oil core surrounded by a HA shell, were loaded with two different drugs, dexamethasone (DMX) and a galectin-3 inhibitor. They presented a particle size in the range of 122-135 nm and a surface charge of − 29/− 31 mV. The gelation time, rheological properties and porosity of the system could be adjusted by different parameters, such as addition of fibrin crosslinkers factor XIII and α2-antiplasmin. The non-crosslinked HA-fibrin hydrogels containing 30% (v/v) NCs showed the capacity to control the release of the encapsulated drug, DMX, for 72 h in simulated synovial fluid. The preliminary in vivo evaluation of the system containing a galectin-3 inhibitor in an acute synovitis rat model showed a suppression of inflammation after IA administration compared with the non-treated control. In brief, this work shows the possibility to combine an in situ forming hydrogel and NCs as a drug delivery strategy for IA administration and suggests its potential for the treatment of arthropathies. Lay Summary This work describes the development and characterization of a new in situ forming hydrogel adapted for intra-articular administration of anti-inflammatory drugs. The prolonged local delivery of these drugs is expected to improve the treatment of large-joint arthropathies. To achieve this objective, the hydrogel, made of biodegradable materials, was loaded with nanodeposits of drugs, named nanocapsules. The efficacy of the system, containing a new galectin-3 inhibitor as a drug candidate, was tested in a rat model of acute synovial inflammation. These results represent the first insights on the in vivo activity of a new galectin-3 inhibitor on a potential galectin-3 immunotherapeutic target for inflammatory joints diseases. Electronic supplementary material The online version of this article (https://doi.