Enciso returns to Suffolk for an undisclosed fee on a five-year contract to 2031, having spent last season playing under O'Neil in France, while Ouattara arrives on a deal running to the same date after also impressing under the head coach at Strasbourg.
The move brings Enciso back to a club he already knows well, following a loan spell from Brighton & Hove Albion in the second half of the 2024-25 season that produced two goals in 13 appearances, including a spectacular strike away at Everton. His season with Strasbourg saw the Paraguayan playmaker contribute 12 goals and nine assists as the French side reached the semi-finals of both the Europa Conference League and the Coupe de France. He arrives off the back of a standout World Cup with Paraguay, scoring the opening goal in a dramatic Round of 32 win over Germany in Boston.
"I am so happy to be back at Ipswich Town," Enciso said after signing. "I really enjoyed my time on loan at the club and I was so happy to see them win promotion back to the Premier League last season.
"I worked with the manager in France last season and the chance to play for him again at a great club like Ipswich is one I'm very excited for. I can't wait to see the supporters again."
Ouattara's move represents a different profile of signing for Ipswich. The 20-year-old Ivorian, capable of playing across both full-back positions or in midfield, made 45 appearances in Ligue 1 and was a key figure in Strasbourg's run to the Europa Conference League semi-finals last season, contributing two goals in 10 appearances in the competition.
"I am very happy to have signed for Ipswich Town," he said. "The Premier League is the best league in the world and as soon as I knew the opportunity was there, to play in England under a manager I have already enjoyed working with, I jumped at it. I am still young but have had some good experiences already and I can't wait to meet the fans and my teammates and get started."
O'Neil welcomed both arrivals as players he already knows well from his time in France.
"We are delighted to bring Julio to the club on a permanent deal," he said. "Supporters will already know what he is capable of, following his loan spell the last time we were in the Premier League, and for me I'm delighted to be working with him again after our time together at Strasbourg last season. He is a young player who is capable of creating something out of nothing and has shown that throughout his career, including at the World Cup in the summer."
On Ouattara, the head coach added: "Abdoul is a talented young player who can play in different positions, so is a very good addition to our squad. We enjoyed working with him in France last season and are delighted to have the opportunity to do so again at Ipswich."
Enciso, born in Caaguazú, joined Libertad's academy at 12 and became the club's youngest-ever player when he made his senior debut at 15, going on to win back-to-back Apertura titles before his 2022 move to Brighton, where a long-range strike against Manchester City was later named the Premier League's Goal of the Season.
He has scored 40 goals in 182 senior club appearances and won 37 caps for Paraguay. Ouattara, born in Zoukpangbeu, moved to France at ten and joined Strasbourg's academy in 2018, making his first-team debut against Paris Saint-Germain in October 2024 before establishing himself as a regular across multiple positions last season.