After a three-month layoff from the ring on May 7, 1949, Castellani defeated Tony DeMicco before 1435 fans in New York's St. Nicholas Arena in a well publicized ten round unanimous decision.

Castellani staggered his opponent in the third round, winning the bout from long range, and defending DeMicco's attempts to fight inside.

In a noteworthy victory on November 14, 1951, Castellani defeated Joey Giardello in a convincing ten-round decision in Scranton, Pennsylvania.

Both judges scored the fight closely, but the referee gave a larger ten point margin to Bratton.

[11] The win moved Castellani to the second round of the World Middleweight Championship tournament to meet Sugar Ray Robinson for the title.

[12][13] On February 6, 1953, Castellani lost to Frenchman Pierre Langlois in twelve rounds before 4,887 fans in a Madison Garden upset Split Decision.

[14] The loss ended Castellani's goal of making an immediate shot at the World Middleweight Title against Sugar Ray Robinson, but he would get his chance at the reigning champion two years later in a non-title bout.

[15] The highlight of Castellani's career was his ten-round split decision near Hollywood, California on July 22, 1955, against Hall of Famer and world middleweight champion Sugar Ray Robinson.

After his knockdown, Robinson rallied quickly, leading the bout with furious body punching which impressed the judges.

The thrilling spectacle which attracted 8,230 featured a close contest between Castellani, the top contender for the middleweight championship and Robinson, who would successfully defend his title against Bobo Olson in his next fight on December 9, 1955.

Robinson called upon all his fifteen years of boxing experience to win the bout against a skilled opponent who was nearly his equal if only for ten rounds.

[16] A year earlier on August 20, 1954, Castellani lost a unanimous fifteen-round decision before a crowd of 11,000 to Carl "Bobo" Olson for the World Middleweight Title in Daly City.

[17] On January 4, 1956, Castellani lost to talented middleweight Gene Fullmer in a televised bout at the Arena in Cleveland, losing in a very close, ten round Split Decision.

[18][19][20] On August 3, 1956, Castellani lost to skilled middleweight Joey Giambra by a significant points margin in a ten-round split decision at Madison Square Garden.

Castellani retreated constantly throughout the first five rounds only rarely moving to make a punch and unable to face the stronger, and better skilled Giambra.

[21] On December 10, 1956, Giambra defeated Castellani again in a ten-round unanimous decision at the Civic Auditorium in San Francisco.

[25] After retiring from boxing in 1957, he became a tavern owner at Rocky Castellani and Sons in Atlantic City and Galloway Township, New Jersey and sponsored local youth sports' teams.