noun
employed person; person who has found employment
Refers to someone who has secured a job, often used in contexts like new graduates entering the workforce or employment statistics.
今年の新卒就職者は前年より増えた。
The number of new graduate hires this year increased compared to last year.
就職者数は景気の影響を受けやすい。
The number of employed persons is easily influenced by the economy.
求職者 means 'job seeker' or 'applicant', someone looking for work, whereas 就職者 is someone who has already secured a job.
Compound of 就職 (shūshoku, 'finding employment') + 者 (sha, 'person'). The meaning is transparent from its components.