The 32-year-old Brazilian attacking midfielder, currently on loan to Sao Paulo, is making a base salary of US$6.6 million and guaranteed compensation of $7,167,500 in 2014, according to figures released by the MLS Players Union.
Kaka signed a 3 1/2-year deal with Orlando this summer.
Seattle Sounders striker Clint Dempsey is second in earnings at $6,695,188.75 ahead of Toronto FC midfielder Michael Bradley ($6,500,000) and TFC striker Jermain Defoe ($6,180,000) with Los Angeles Galaxy attacking midfielder Landon Donovan fifth ($4,583,333.33).
The rest of the top 10 is Galaxy striker Robbie Keane ($4,500,000), New York Red Bulls forward Thierry Henry ($4,350,000), Red Bulls midfielder Tim Cahill (3,625,000), New England Revolution midfielder Jermaine Jones ($3,252,500) and Montreal Impact forward Marco Di Vaio ($2,600,000).
Attacking midfielder Pedro Morales leads the Vancouver Whitecaps at $1,410,900.
Other league millionaires includes Seattle striker Obafemi Martins ($1,753,333.33), Los Angeles defender Omar Gonzalez ($1,250,000) and Toronto forward Gilberto ($1,205,000).
Among the new faces on the updated salary list are Portland Timbers defender Liam Ridgewell ($1.2 million) and Houston Dynamo midfielder DaMarcus Beasley ($797,166.67).
New York City FC's first signing David Villa is listed at just $60,000, a small down payment no doubt on his future earnings.
Sporting Kansas City forward Dom Dwyer is a bargain at $92,500. He's currently second in league scoring with 20 goals.
Red Bulls forward Bradley Wright-Phillips tops the scoring table with 24 goals. He makes $372,500.
Portland playmaker Diego Valeri, second to Donovan with 14 assists this season, is another bargain at $500,000.
Timbers captain Will Johnson, a Canadian international who broke his leg in Toronto on the weekend, is listed at $372,500.
Defender Steven Caldwell, Toronto FC's captain, makes $364,166.67, although the figure in his and some other cases could be higher through allocation money and other ways of paying down salary numbers.