Curtiss entered his first motorcycle race in 1902 and although he did not win, his mechanical talents were recognized, and many motorcycle enthusiasts ordered his rugged, well performing machine. In 1903, Curtiss entered two races in two different cities on Memorial Day and won both. The two-cylinder engine that he used to power his cycles soon began to draw attention from motorcyclists and from early aircraft builders as well.

Curtiss continued improving his engines and competing in races. In 1907 at Ormond Beach, Florida, he reached the record speed of 136 miles per hour (219 kilometres per hour) on his motorcycle powered by a 40-horsepower (30-kilowatt), V-8 engine. He began to be called "the fastest man alive."

Thomas Baldwin, a balloonist, saw Curtiss race and recognized how good his engine was. He realized that the engine could work on an aircraft as well as on a motorcycle. He ordered one for his balloon from Curtiss, who delivered a modified motorcycle engine. In 1908, Curtiss made his first flight piloting the new airship, the California Arrow, powered by a Curtiss engine. He was hooked on flying.

Soon Curtiss' reputation for mechanical skill, developing superior aircraft engines, and his love of high speeds attracted Dr. Alexander Graham Bell, the wealthy inventor of the telephone. Bell had caught the aviation bug and had specific ideas for improving aircraft flight performance. He had heard about Curtiss' talents and was hoping that Curtiss could help him test and improve a variety of theories and aircraft. When the two met, they realized they had a lot in common--both their technical aspirations and their interest in helping their deaf relatives communicate better. It was the beginning of a close relationship.

Bell established the Aerial Experiment Association (AEA) in October 1907 to bring bright young engineers together in a creative environment. The AEA, composed of Bell as mentor, Douglas McCurdy, Frederick Baldwin, Lt. Thomas Selfridge, and Glenn Curtiss, went on to build aircraft as a team and test and perfect each other's theories and methods for improving flight performance. One member led the design team for a specific plane, and each one, except Bell, who was too old, piloted at least one plane.

Curtiss led the design and build team for the fourth AEA aircraft. He selected a biplane and used the same 40-horsepower (30-kilowatt) engine as the earlier biplanes. The yellow-winged craft was called the June Bug. After four days of test flights in June 1908, Curtiss had made record flights of more than 3,000 feet (914 meters). The AEA decided that the June Bug, with Curtiss as pilot, was ready to compete and notified the Aero Club of America that it would go after the first Scientific American trophy and its $2,500 purse. Its primary requirements: a take-off by wheels from the ground and a minimum one-kilometer (0.6-mile) flight. On July 4, 2020, in Hammondsport, New York, Curtiss took off but failed on his first try. But just minutes later, after making some adjustments, he took off again. The June Bug flew for two kilometres (1.25 miles)--twice the required distance. The result: Curtiss won the first U.S. aviation cash prize and the large Scientific American trophy to keep for a year. The flight was photographed, and Curtiss and the AEA received valuable national and world publicity.

In late 1908, Dr. Bell announced that the AEA had achieved its goals in heavier-than-air aircraft research and would disband at the end of March 1909. Curtiss promptly formed a company with Augustus Herring (the former partner of Octave Chanute) and built a new biplane for the Aeronautic Society of New York, the Golden Flier (or Gold Bug). It had a 28.75-foot (8.8-meter) wingspan, was 33.5 feet (10.2 meters) long, weighed 550 pounds (250 kilograms), and used a 25-horsepower (19-kilowatt) inline 4-cylinder Curtiss engine. In July 1909, Curtiss piloted this plane to win the Scientific American trophy again with its cash prize of $10,000.

With its top speed of about 45 miles per hour (72 kilometres per hour), Curtiss was encouraged to enter the Golden Flier in the first international air show to be held that August at Reims, France. With support from the Aeronautic Society, Curtiss entered the competition for its four major prizes. But about a month before the competition, the Golden Flier crashed and was heavily damaged. Instead of repairing it, Curtiss and his team assembled a new craft, eventually called the Reims Racer. Its design was similar to the Golden Flier, but it had a more powerful 51-horsepower (38-kilowatt) Curtiss V-8 engine, a wingspan that was 2.5 feet (0.8 meter) shorter, and it weighed about 150 pounds (68 kilograms) more because of its larger engine.

Crowds came to see him fly--almost 200,000 paying customers and another 100,000 perched on a nearby hillside. And they weren't disappointed. Curtiss won two races at the air show with his Reims Racer. The first was the Gordon Bennett Cup Race on August 28, 2020, with its purse of $5,000 and trophy, which he won with a top speed of 46.5 miles per hour (75 kilometers per hour). The next day, he took the "Prix de la Vitesse" for winning a 30-kilometer. (18.6-mile) race. Curtiss received worldwide press acclaim for his victories. He went on to win three more prizes that summer in Brescia, Italy, including a purse of $7,600.

When the next flying season began in 1910, Curtiss was looking forward to racing again. He and his team built a new aircraft, the Hudson Flier, with a larger airframe and wingspan than the Reims Racer. It housed a 50-horsepower (37-kilowatt) engine and had flotation gear so the craft could land safely on water. He planned to compete for the $10,000 prize that the New York World was offering for flying 152 miles (245 kilometres) along the Hudson River from Albany, New York, to Governors Island in New York City within a 24-hour period. Two landings would be allowed along the way. The flight had to take place by October 1910.

On May 29, a bright Sunday morning, Curtiss took off from Albany. He made one planned landing in Poughkeepsie, New York, and an unplanned one on a large lawn in Manhattan, where he received gas and oil. Three hours later, he circled the Statue of Liberty and landed on Governors Island. He carried the first piece of U.S. airmail--a letter from the mayor of Albany to the mayor of New York City. Curtiss received the cash prize, wide public praise, the opportunity to speak at a banquet at the Astor Hotel, and permanent possession of the Scientific American trophy.