The town's name is derived from 'big man' in a local Aboriginal language.
The railway arrived in the area in 1906. There had not been any significant development in the area before that, as the remoteness and difficulty of getting supplies in and produce out had made it uneconomic to farm before that.
The Border Times is a weekly newspaper published in the town.
The Town has a large variety of sports for a town of 900, such as Australian Football, Netball, Cricket, Tennis, Basketball, Volleyball, Lawnbowls, Badminton, Golf and darts. The towns local football team, the Pinnaroo Supa Roos play in the Mallee Football League.
Pinnaroo also has a show and field days every year at the start of October. The Pinnaroo Show features dog trials, agricultural tents, competitions, horse events, keg tosses, animal judging and fireworks. The Show attracts over 10 000 people every year. Another event Pinnaroo hosts is the Pinnaroo SpudFest. The SpudFest features a black tie dinner, stalls and games, entertainment, and Spud Wrestling.
The railway is not currently available for transport between the states, as it was converted to standard gauge from Tailem Bend soon after the main Adelaide–Melbourne line was converted, but the line to Ouyen remains as broad gauge. Both sides are used to transport grain from silos along the railway line towards the ports in each state.
The town has also become a major centre for growing potatoes since around 1990.
The postcode for Pinnaroo is 5304. Pinnaroo is the seat of the Southern Mallee District Council, and is in the South Australian House of Assembly electoral district of Hammond and the Australian House of Representatives Division of Barker.
Pinnaroo Primary School is a public primary school for students in grades reception to 7, and has approximately 70 students. The school has four composites classes - Reception, Grades 1, 2 and 3, Grades 4 and 5, and Grades 6 and 7. It is the only school within 30 km of the town. As of 2008, the school's principal is Paul Pitkin and the school slogan is Aim High. The school regularly takes part in interschool sports with neighbouring schools Lameroo and Geranium in swimming and athletics. The school also takes part in SAPSASA with the Murray Mallee team in sports such as Australian Rules Football, Cricket, Athletics, Swimming, Golf, Softball, Tennis, Netball, Basketball and Badminton. The school has four class-rooms, a GP room, an art and technical centre, a home economics centre, an FM radio station, a swimming pool, two ovals, outdoor tennis, netball and basketball courts, and a full size gymnasium.
Pinnaroo Primary School is the home of South Australia's first Community Library which opened in 1974.