An injury crisis early in 2006–07 season under new manager Leroy Rosenior saw Osborne make regular substitute appearances in youthful matchday squads through the first six weeks of the season, before he broke into the starting lineup at right back in late September 2006. He made 24 appearances during a disastrous season, which ended with Brentford's relegation to League Two. Osborne signed a new two-year contract in June 2007 and made semi-regular appearances during the 2007–08 and 2008–09 League Two seasons.