The winger left Arsenal after the two parties mutually agreed to terminate the final year of his contract, according to transfer journalist Fabrizio Romano, who reports Nelson has since passed a medical and put pen to paper with Feyenoord.
The move brings an end to 18 years associated with Arsenal, a spell that began in the club's academy and included a breakthrough into the first team before injuries and limited opportunities under Mikel Arteta pushed him toward a series of loan spells away from the Emirates.
Nelson already knows Feyenoord well, having spent the 2021-22 season on loan in Rotterdam under then-manager Arne Slot. He scored four goals and provided seven assists in 32 appearances during that spell, playing a significant role as the Dutch club reached the final of the inaugural Europa Conference League.
His familiarity with the club and its supporters made a reunion an appealing option once his Arsenal departure was confirmed.
The 26-year-old made 90 senior appearances for Arsenal in total, scoring eight goals and providing nine assists, but was unable to establish himself as a regular starter despite signing a contract extension in 2023. Subsequent loan spells at Fulham and, most recently, Brentford did little to change his circumstances at the Emirates, eventually leading both player and club to conclude that a permanent exit was the best path forward for his career.
With the move completed as a free transfer, Feyenoord have been able to negotiate his arrival outside the normal constraints of the closed transfer window, giving the club a low-risk opportunity to add proven Eredivisie pedigree to their wide attacking options for the season ahead.
There had been earlier talk of a move to West Ham United for a fee in the region of £3million, but the London club were reported to be stalling on the deal while exploring other options, with no guarantee they would have pushed the move through before the deadline.
Arsenal's decision to terminate his contract rather than negotiate a straight sale gave Nelson greater freedom to weigh his options, and a return to a club where he remains fondly remembered ultimately proved the most attractive path forward for a player looking to rebuild momentum in his career.