Bailey-Gayle, 22, represents Jamaica on the international stage and started out in Arsenal's youth system.
The forward made her debut for the Gunners' first team in 2018 and also played for Leicester City Women before moving to Palace in 2022.
Cataldo, also 22, began her career with Millwall Lionesses and represented Arsenal Women, London City Lionesses, Leicester City Women and Bristol City Women before signing for the Eagles in August 2023.
The former England youth international helped the Robins win the Championship last season and, with Bailey-Gayle, the duo arrive on Tyneside as the Magpies strive to achieve promotion from the FA Women's National League Northern Premier Division.
Of Bailey-Gayle, Newcastle boss Becky Langley said: "Paige is a fun, energetic and great character. She's got experience of being involved with Jamaica at a World Cup and is an exciting attacking player.
"She's quick and has good technical finishing qualities, as well as experience of winning the Championship with Leicester, so hopefully this will help the group."
Langley added: "We are really excited to get Lia on board too. She's a player with experience at Bristol City, Leicester and Crystal Palace, and won the Championship for Bristol City and Leicester.
"She's got a fantastic physical and technical profile, and she's also a lovely person so she will be a good team player for us."
Upon signing, Bailey-Gayle said: "It is a really good club with a lot of history and a bright future so I am happy to join a club that has ambitions that I would love to be a part of.
"I am really excited to get started."
Cataldo added: "I'm so excited to join such a massive club.
"Their ambitions match my own in terms of working the way up and hopefully getting promoted to the WSL in the next few years.
"I am aware that Newcastle have put a massive investment into the women's team so I am really looking forward to getting in with the girls and getting started."
The pair are Newcastle Women's third and fourth signings of the January transfer window, following goalkeeper Lilie Woods and winger Beth Lumsden's arrivals last week.
