He made his international debut in November 2002 in a 35–3 victory against Canada.
Since the retirement of Fabien Galthié, Yachvili has been in and out of the starting 15 but can always be relied upon to produce. What Yachvili also provides is a dependable boot. When Frederic Michalak misfires Yachvili can be called upon to take penalties and conversions, a job he also does for his club side Biarritz Olympique.
During the 2005 Six Nations Championship he regained his position as the first choice scrum-half for the French national team, cementing his position with a virtuoso goal-kicking performance against England at Twickenham. He also captained the French national team, surrendering the captaincy permanently for the 2005 summer tour to South Africa, which he missed through injury.