Nickel nanoparticles (NiNPs) have been the subject of extensive research over the past decade for a wide range of possible applications due to their exceptional strong catalytic activity, high compressive strength, free radical scavenging, and antibacterial property. In consequence of this, there has been a significant advancement in the methods of producing NiNPs, as well as in the suggested reaction processes and applications of these particles. The production, reaction mechanisms, and practical uses of NiNPs are reviewed in this work. NiNPs with sizes ranging from 1 to 100 nm can be manufactured in a number of different ways for use in both scientific and commercial contexts. Synthesis methods are divided into two categories: top-down methods and bottom-up methods which are subdivided into physical, chemical, and biological strategies. Extensive description has been given for the chemical processes involved in the creation of NiNPs, in particular those involved in biosynthesis approaches. The latest developments in the use of NiNPs in industries such as biomedicine, dye absorption, catalysis, supercapacitors, and dye-sensitized solar cells are reviewed. This work also provides examples of the benefits and functions of NiNPs in catalyzing various processes.