He then progressed to the major junior Western Hockey League (WHL) with the Calgary Hitmen after being traded from the Vancouver Giants in exchange for Jamison Orr.

Ladd turned professional after two seasons with the Hitmen in 2005–06 with the Lowell Lock Monsters, the Hurricanes' American Hockey League (AHL) affiliate.

He was called up to the Hurricanes in November, making his NHL debut, but soon suffered a knee injury in December which sidelined him until February.

Ladd was assigned back to the Lowell Lock Monsters until March when he was recalled to join the Hurricanes for their playoff run.

By joining the Blackhawks, Ladd was reunited with three former minor hockey teammates, Troy Brouwer, Brent Seabrook and Colin Fraser, who all played together with the Pacific Vipers.

Ladd and the Blackhawks would go on another lengthy playoff run by defeating the seventh seeded Nashville Predators in six games, the third seeded Vancouver Canucks in the six games in the second round for the second straight year and sweeping the top-seeded San Jose Sharks in the Western Conference Finals before defeating the seventh seeded Philadelphia Flyers in six games in the 2010 Stanley Cup Finals as the Blackhawks won their first Stanley Cup since 1961 and fourth in franchise history and the second Stanley Cup of Ladd's career.

[4] On July 1, 2010, in a salary-cap move, Ladd was traded to the Atlanta Thrashers in exchange for defenceman Ivan Vishnevskiy and Atlanta's second-round choice in the 2011 NHL Entry Draft (used to select Adam Clendening), joining Dustin Byfuglien, Ben Eager and Brent Sopel, who had been traded from the Blackhawks a week earlier.

[10] In the 2015–16 season, in the final year of his contract and with the Jets out of playoff contention, on February 25, 2016, Ladd was traded back to the Blackhawks (along with Jay Harrison and Matt Fraser) in exchange for Marko Daňo and a 2016 first-round draft pick.

The subpar performance of Ladd and other Islanders players led to the mid-season firing of head coach Jack Capuano on January 17, 2017.

In January 2021, in preparation for the pandemic-shortened 2020–21 season, Ladd was re-assigned to directly join the Bridgeport Sound Tigers training camp.

[21] Prior to the 2022–23 season, it was announced Ladd failed his physical due to a nagging knee issue and would spend the last year of his contract on the injured reserve.