Charlotte will receive two future second-round picks and send a conditional future second-rounder to the Celtics. Boston will receive a trade exception in the deal.
Hayward had reportedly agreed to a four-year, $120-million contract with Charlotte earlier in November. However, rather than simply absorbing Hayward's salary into their open cap space, the Hornets and Celtics opened discussions on a potential sign-and-trade that would benefit both teams.
In Boston's case, the expected $28.5-million trade exception created - Hayward's assumed first-year salary in his new deal - would be the largest in the NBA's history, according to ESPN's Bobby Marks.
A trade exception lasts one year from the day it's created. It allows a team over the cap to acquire a player in a trade without having to send offsetting salaries in exchange.
The move officially brings an end to Hayward's stint in Boston following three injury-marred seasons. He missed nearly his entire first year with the Celtics after suffering an ankle fracture five minutes into his team debut and struggled to return to the form he displayed with the Utah Jazz.
Hayward averaged 13.9 points, 5.4 rebounds, and 3.6 assists in three seasons with Boston and appeared in just 125 games.