Gilbert Agius was born on February 21, 1974 in Pieta but was brought up in Valletta. Football is in his blood, he is the son of Charles Agius, a popular attacker for Valletta F.C.
Young Gilbert inherited a lot from his father, especially his uncanny ability to score goals. A product of the Centru Sportiv Marsa, where his father was one of the coaches, he was groomed for a successful career. He started his football apprenticeship with Stelmar but it was with Valletta’s junior strings that he started to show his potential.
Gilbert had his first taste of big-time football on September 2, 1990 when he played as a substitute in a match against Sliema Wanderers (2-3). He played his full match in August of the same year against Hamrun Spartans. Although only 16, he played like a veteran and it was not long before he won a regular place in the first team.
The first memorable moment in his career came in November 7, 1993 when he made his full international debut for Malta in the 2-1 victory against Gabon. Over time, as he gained more experience, he established himself as one of the top strikers. He scored his maiden international goal when Malta lost 2-1 to Iceland in a friendly in Reykjavik on 14 August 1996. 
Gilbert’s career happily coincided with the greatest time in the history of Valletta F.C. Indeed he was one of the main protagonists. In 1996-97, the Citizens won all five major honours available in the football calendar. He capped a fantastic season by winning also the Footballer of the Year award. It was a fitting tribute to this prolific goal-scorer whose superb contribution was a major factor to Valletta’s clean sweep of the honours.
Agius repeated this feat in season 2000-01, only this time he went one better. That season was the greatest in the history of the club. Valletta became the first and possibly the only team to win six trophies in one season. Besides collecting all six medals, Gilbert crowned his breathtaking performances in all six competitions by winning the Footballer of the Year for the second time. Agius scored 26 goals in competitive matches during that golden season, including a grand hat-trick against Rijeka of Croatia in the UEFA Cup competition. Gilbert won the Footballer of the Year for the third time in season 2006/07.
By the time he was 27, Agius had already collected enough honours to fill the showcase. However, season 2001-02 was anti-climax after the euphoria of the previous season. In September he signed a contract with Pisa in the Italian Third Division. He stayed in Italy up to January 2002 but looking back it seems to have been a bad experience for him. Life as a professional footballer is not a bed of roses, as many people seem to think. Gilbert failed to command a place in the first team and this, together with other difficulties, influenced his decision to return home and continue his career with Valletta.
On 7 February 2007, Gilbert scored his eighth and final goal for the national side earned a 1-1 draw with Austria, also in a friendly. During August 2007, Gilbert Agius flew out to Sweden on a trial with second division club Enkopings SK. The Swedish club showed great interest in signing him until the end of their domestic season and Agius also extended his trial to another week. However Gilbert returned back and continued playing with his home-town team Valletta F.C. 
Gilbert Agius made his 400th league appearance for the club on April 23, 2010 nearly 20 years after his debut against the same opposition Sliema Wanderers.
October 2011, Gilbert received a commemorative cap and medal from UEFA to mark his century of international appearances.

Gilbert made a total of 612 appearances for Valletta and scored a total of 241 goals. He holds the record for most appearances and all time top scorer.
During summer 2012, he was appointed assistant coach to Mark Miller and was also the coach of the Valletta Under-19 side.
In season 2013-2014 at the age 0f 39, Gilbert came out of retirement in order to continue his football career, he signed a contract till the end of the season with Gozitan outfit Xewkija Tigers. This was a return to Gozitan football for the former captain of the national squad, having played with Victoria Hotspurs in the early 90s. At the end of the season Gilbert also won the First Division title with the Tigers in Gozo.
In May 2014, Gilbert returned back with Valletta and this time was appointed coach.
The Maltese international was capped for 119 games with the national squad, scoring eight goals. He won the league eight times and won the MFA player of the year three times. Throughout his career Gilbert played a total of 453 matches in the Premier League and scored 182 goals. In a career spanning over 23 seasons, he played a total 769 matches and scored 254 goals, in all competitions wearing the City’s white shirt.