。
She turned down my request.
Literal
She [topic-は] my request [object-を] declined.
依頼 is the formal Sino-Japanese word for 'request, commission, entrustment' — distinct from お願い (everyday 'request, please') and the more transactional 注文 (an order). 依頼を断る pairs naturally as 'decline a request,' fitting business or formal contexts where someone is being asked to take on a task. The same verb 断る used earlier with 招待 (invitation) — turning down anything formal in Japanese typically uses 断る; お断りする raises the register to keigo.