Bird, who has played three Tests for Australia, will be available in all formats for three months ahead of his potential involvement in the Ashes. His ability to swing the red ball will be valuable in April and May, with Hampshire returning to Division One of the Championship. Bird was due to play for Northamptonshire this season but was prevented from appearing by injury.
Arafat will make Hampshire his sixth county - equalling Marcus North's record for an overseas player - and be available for Royal London Cup and T20 Blast games. Arafat played for Sussex in 2014 and has previously turned out for Kent, Lancashire, Somerset and Surrey.
The former Pakistan international, a regular in T20 competitions around the world, is married to an Englishwoman and lives in Kent but Giles White, Hampshire's director of cricket, suggested Arafat's "qualification status may allow him to play as a local during his time with us".
"We're delighted to have Jackson and Yasir on board for next season - they will both add a lot of quality to our bowling attack and hopefully they will help us build on a successful 2014 season," White said.
"Jackson comes highly recommended and at a time of the year that is likely to suit his style of bowling, we are looking forward to having him about and hope he has a positive influence on our return to Division One. Yasir has the flexibility to play all of our one-day cricket, boasts an excellent record and has committed to the club for further campaigns."
South Africa seamer Kyle Abbott played a big role in Hampshire's 2014 promotion campaign, taking 36 wickets at 20.33, and Hampshire could attempt to re-sign him for the second half of next season. Abbott's availability will be dependent on his involvement with South Africa, who are scheduled to tour Sri Lanka and Bangladesh during the English season.
"Kyle Abbott is someone we will continue to keep in touch with as he fitted into the group exceptionally well this year and has voiced a desire to return if international commitments allow," White said.