Barnard signed for Southampton on 22 January 2010 for an undisclosed fee, with Matt Paterson joining Southend. He had scored 17 goals in all competitions for Southend in the 2009–10 season. He made his debut the following day against Ipswich Town in the FA Cup in a 2–1 win. He made his league debut for the club on 26 January, against Brentford in a 1–1 draw. On 20 February, Barnard scored his debut league goals for Southampton, against title challengers Norwich City, scoring both goals in the 2–0 win which saw the end of Norwich's 11-match winning run. A week later he showed the same form as he netted a brace against Walsall in a 5–1 victory, and then scoring again three days later in the 5–0 win over Huddersfield Town. In the 2010–11 season he scored twice against Yeovil in a 3–0 victory and four days later scored the first goal in a 3–1 away win at Bournemouth. He finished the season with 16 goals, but missed the last few weeks due to injury.