The Swiss driver first appeared in a Formula One event during what would undoubtedly be considered his home grand prix, the Swiss Grand Prix. Driving for Scuderia Achille Varzi, Branca was able to finish the race in a 4CLT in 11th place, well out of the points.
His best result in a Formula One event in 1950 came at the only other race in which he contested. It was the next round of the championship and it took place in Spa, Belgium and was the Belgian Grand Prix. Driving under his own team name, Branca managed to finish the 35 lap race in 10th. Branca was driving the sole Maserati.
1950 had been a busy year for Branca. He had raced in eleven events and experienced varying results. But, mostly the results were poor. He only managed to finish two races in the top-five and those two results came in lower Formula 2 class races.
Heading into the 1951 season, Branca changed. The costs of the upper-levels of grand prix racing were quite expensive. This cut down on the number of races in which the Swiss driver would end up competing. In all, he would only take part in four races throughout the whole of the season. However, each one of the four races were either Formula One events, or, still what were considered the top-levels of grand prix races.
Whether it was planned, or, it was the result of financial issues or something else, Branca's season didn't get going until the middle part of summer. There was no rush to blow money when only competing in a few races.
Therefore, Branca waited and was ready when the Formula One season pulled into Nurburg, Germany for the German Grand Prix. Branca had decided to miss his own Swiss Grand Prix, but, he would have the privilege (if that is what the drivers of the day considered it?) to race on the notoriously long and twisty, 14 mile long Nordschleife.
Twenty-two cars drivers qualified their cars for the 20 lap race through the forests of Germany. Alberto Ascari set the fastest time in his Ferrari 375 and would, therefore, start the race from the pole. By this point in the season, Ferrari had been starting to put the squeeze on Alfa Romeo, who was struggling in their own right due to financial problems. Ferrari drivers started the race 1st, 2nd, 5th and 6th. Fangio and Farina were sandwiched in between starting 3rd and 4th. Branca's best time was nowhere near that set by the front-runners. In fact, Branca's time was only good enough for him to start from 17th on the grid. The older Maserati 4CLT/48 was a good car but could not provide the performance necessary to be truly competitive on the long Nordschleife. Being competitive would end up being the least of Branca's issues.
Race day emerged with a dry track and lots of sunshine. But the sun wouldn't shine on Antonio. The cars pulled away at the start of the race. Initially, Jose Froilan Gonzalez, Alberto Ascari and Juan Manuel Fangio were mixing it up at the front. It wasn't too long before the track started to claim its victims.
On the second lap of the race (of course one lap on the Nordschleife is more like four on a regular grand prix course), de Graffenried's engine in his Maserati expired. This would not bode well for the other entrant driving a Maserati, which was Branca. Sure enough, on the very next lap, the engine on Branca's Maserati let go as well. He had only been able to finish two laps or about 28 miles of the race before he was forced to retire.
This was only Antonio's third Formula One race, but, it would end up being his last. Of the three Formula One events in which he participated, the best result he had been able to achieve happened the year before at Spa-Francorchamps. At the Belgian Grand Prix in 1950 he had been able to finish 10th. Totaling the sum of Branca's experiences in Formula One it is found he never led a single lap of any race, he never set a fastest lap at either of the races, he had never won one of the races, nor had he ever finished in the points.
Although Branca was done in Formula One for 1951 and for the rest of his career, he wasn't done racing in non-championship races throughout the rest of that year.
After the disappointing race on the long Nordschleife, Branca followed up one long race course with another. In the middle of August that year, Antonio headed to Pescara to take part in the grand prix of Pescara. The grand prix in Pescara took place on a course layout that was even longer than that of the Nordschleife. Made up of coastal city streets and farming countryside, the course for the race was just under 16 miles in length. Just one lap took nearly eleven minutes to complete. In the case of Branca and his older Maserati it would take longer.
Scuderia Ferrari came with three of their Ferrari 375s and one 125. The course was a relatively higher-speed venue, which favored the prancing horses. Ascari took the pole with a lap time of ten minutes and forty-three seconds. Teammate Villoresi was 2nd with a time just over five seconds slower. Louis Chiron was able to push his Talbot-Lago T26C to a good starting position in 3rd. His time was almost a full minute slower than Ascari's. That wasn't all that bad when compared to the performance gap with which Branca had to contend. His best time was two minutes and about forty seconds slower. This meant Antonio started the race from 10th on the grid.
Despite the performance deficiency, Branca's race turned out to be rather good. As the field headed off at the start of the 12 lap race, Ascari didn't go anywhere. His 375 had oil pressure problems. This led the team to make the decision for Ascari to take over Villoresi's car. It didn't matter. Four laps into the race with Villoresi's car, transmission problems hit and left Ascari stranded again. This boded well for other drivers and teams since two Ferraris were out the picture. Branca would be one of those that would be able to benefit from the troubles.
The other Ferrari teammate, Gonzalez, would go on to win the race by a margin of over seven minutes. Louis Rosier finished 2nd, and was followed another two minutes further behind by Philippe Etancelin in 3rd. Antonio Branca wasn't fortunate enough to stay on the lead lap with Gonzalez, but he was fortunate to finish a splendid 6th.
Branca's next race was the Grand Prix of Bari in the very early days of September. The field was filled with Alfa Romeos and Ferraris. Their presence meant there would be difficulty in achieving a good result. Qualifying proved this. Branca started the race 16th. But, all the performance in the world doesn't matter if one isn't able to finish the race. This was Branca's problem. Six laps into the race, Branca's Maserati suffered a problem with the oil pump and forced the Swiss driver to have to retire from the race.
Branca's last race of 1951 would leave a lasting impression on him. At the end of September he headed to Chichester, England, and the Goodwood circuit, to take part in the 4th Goodwood Trophy race. The race was short; only 15 laps. But it would be the first lap that would be the most memorable for Branca.
Seventeen drivers started the race. Branca started next-to-last on the grid. On the very first lap of the race, he and Brian Shawe-Taylor came together in a horrifying accident. Shawe-Taylor was severely injured but managed to live. Branca wasn't injured as seriously, but it was enough for him to firmly decide to step aside from the upper-classes of grand prix racing.
After leaving Formula One and upper-classes of grand prix racing, Branca continued to be spotted at different, more local, racing events, especially hillclimbs. He would continue to race in the minor classes of grand prix racing and even had a couple of stabs at the 24 Hours of Le Mans that ultimately proved to be un-fruitful. As time slipped into the '60s, Branca, too, began to slip out of sight. The man from Sion, Switzerland died in Sierre in May of 1985 at the age of 68.