Famalicão Costa has been with
Famalicão since his teenage years. He progressed through the ranks and represented the club in various age levels, from under-15, under-17, under-19, and under-23 national competitions, captaining nearly every age group he has played in. Costa signed his first professional contract on 3 September 2021. He then signed a contract extension till 2026 on 21 March 2023.
2023–24: Loan to Académica Costa was loaned to Portuguese
third tier club
Académica in the second half of the
2023–24 campaign. He made a total of 12 appearances for the club.
2024–25: Called up to senior side and loan to Lion City Sailors Costa mainly played in the Liga Revelação. He was also named on the bench three times for Famalicão's senior side in the first half of the
2024–25 Primeira Liga season. He wore the number 75 for the senior side. In the second half of the season,
Singapore Premier League club Lion City Sailors announced the signing of Costa on loan from Famalicão until the end of the
2024–25 Singapore Premier League season on 25 January 2025. Costa made his Singapore Premier League debut on 26 January 2025, in a 2–1 win against
Geylang International. Costa made his
AFC Champions League Two debut in the first leg of the
Round of 16 match against
Muangthong United. Costa won his side a penalty after a mazy run into the box. Despite being a man down early in the second half, Diogo demonstrated his defensive prowess, playing a key role to protect their lead. The matched eventually ended in a 3–2 victory to the Sailors. Costa made a hat-trick of assists, all for
Lennart Thy, in a 8–0 win over
Young Lions on 6 April 2025. Costa made two assists for
Bart Ramselaar and Lennart Thy in the first leg of the AFC Champions League Two semi-finals against
Sydney FC. The matched ended in a 2–0 win at
Jalan Besar Stadium. Despite a 1–0 defeat to Sydney at the
Allianz Stadium, Costa helped the Sailors to create history, booking their spot in the
final with a 2-1 aggregate victory in the semi-finals. Costa assisted Lestienne in the final against
Sharjah. However, the Sailors were unable to hold on and eventually conceded in the 97th minute to finish the game in a 1–2 defeat. Costa made 4 assists in 7 games in the Champions League Two campaign. Costa scored his first professional goal in the second leg of the semi-final match against DPMM in the
2024–25 Singapore Cup. Costa ended the season winning the Singapore Premier League, the Singapore Cup and finished as a runner-up in the AFC Champions League Two. He recorded 11 assists in 21 games across all competitions.
Lion City Sailors On 8 July 2025, it was announced that Costa would be staying at the Singaporean club after signing a permanent five-year contract. Costa scored his first league game in a 7–0 victory against
Tanjong Pagar United on 22 September. ==Style of play==