[7] The transition was a success and, by the age of 13, Ruffier had acquired the physical skills and traits needed to excel at the position.

[7] While in the youth system of Bayonne, Ruffier helped the club's under-13 team win the Coupe de Pyrénées.

[8][9] Following the season, Monaco loaned Ruffier back to his former club Bayonne with hopes that the youngster would get some consistent first-team playing time.

He responded by playing in all 38 league matches, but could not prevent the team from suffering relegation to the CFA as the club finished in 17th position.

Ruffier made his professional debut in the match appearing as a substitute in the 58th minute for Roma and maintained the team's 1–0 lead.

[12] In the team's next three matches, Ruffier played the full 90 minutes in victories over Sochaux, Le Mans, and Lille.

In the 2008–09 Ligue 1 season, manager Ricardo Gomes decided to retain Ruffier as the team's number one goalkeeper.

Ruffier appeared in 36 total matches recording eleven clean sheets, which included blanking Paris Saint-Germain on two occasions and holding off Marseille at the Stade Vélodrome with the hosts outshooting Monaco 22–4.

In the Coupe de France, he earned three clean sheets as Monaco reached the 2010 edition of the cup's final match.

In the final, Ruffier maintained a clean sheet for over an hour and a half before conceding a Guillaume Hoarau header in extra time.

[4] In the opening match of the season against Olympique Lyonnais, Ruffier dueled with French international and first-choice goalkeeper Hugo Lloris.

[27] In the latter half of the 2019–20 campaign, Ruffier came into conflict with manager Claude Puel after being dropped from the starting lineup in favour of Jessy Moulin.

However, coach Raymond Domenech preferred Cédric Carrasso as the team's third-choice keeper and took him, along with Lloris and Steve Mandanda to the 2010 FIFA World Cup.