Jeffries, 24, is 6-foot-5 and appeared in a total of 31 games with the Kings and Rockets last season, averaging 4.1 points and 2.3 rebounds. He also spent 13 games with the Kings as a rookie in 2019-20.
Lawson, 21, is 6-6 and went undrafted out of South Carolina this past summer. He initially signed with the Heat, but joined the Hawks for summer league. Atlanta signed him to a training camp deal last month.
The Hawks have 14 players under contract, with a 15th roster spot available should they decide to use it.