The 23-year-old Egypt international won three consecutive Super League titles with Basle and also played in European competition
Elneny is expected to offer some much-needed cover in midfield, with the likes of Jack Wilshere and Santi Cazorla still recovering from injury
Arsenal added the deal was "subject to the completion of regulatory processes", but hope Elneny could feature in the squad at Stoke on Sunday
Manager Arsene Wenger will hope the confirmation of Elneny's transfer will give his side a timely boost after they dropped two points at Anfield on Wednesday night
Just when it seemed the Barclays Premier League leaders underlined their title credentials by twice coming from behind to go 3-2 ahead, the visitors conceded an added-time equaliser to Liverpool substitute Joe Allen
The draw allowed Leicester to join Arsenal at the top of the table following a late winner at Tottenham, and represented a missed opportunity to put more ground between themselves and third-placed Manchester City, who were held to a goalless draw by Everton
It left the Arsenal manager frustrated and even the conclusion of the drawn-out transfer of Basle midfielder Elneny, which has been held up by visa paperwork, could not lift his mood
Elneny has to be registered by noon on Friday to be eligible to play at Stoke on Sunday and Wenger is hopeful that will be done
''He has joined us and we will see if he can qualify for Sunday,'' he said.
Source : PA
Source: PA