The 2011–12 season was the big breakthrough for John at Twente, as he got a starting place from Co Adriaanse at the start of the season, and did not lose that even with competition for the left forward position, as Nacer Chadli returned from injury. He also topped the UEFA Europa League group stage assist rankings with six assists. In Twente's home match in the Europa League against Odense BK on 3 November, John provided all three assists in a 3–2 win. John was influential in the Eredivisie campaign as well, netting two goals in a 6–2 victory over FC Utrecht on 4 December 2011.
Benfica and loans
On 24 May 2012, John signed for Portuguese club Benfica on a five-year deal which included a €45 million release clause for a transfer fee of €9.1 million according to Football Leaks. It was rumored that 80% of the undisclosed went to sports investment company Doyen Sports. After struggling to find his space in the first team during his initial months in Lisbon, John became a regular starter or used substitute in the second half of Benfica's 2012–13 campaign, which included appearances in UEFA Europa League and Portuguese Cup finals. He was loaned to Hamburger SV for the remainder of the 2013–14 season on 17 January 2014. He stayed at Benfica for the new season, scoring his first league goal on 12 September 2014 against Vitória Sétubal. On 5 October, he gave two assists in a 4–0 home win against Arouca in Portuguese league. On 29 May 2015, John scored the winning goal against Marítimo in the league cup final. On 1 September 2015, John was loaned out to Football League Championship side Reading for one season. Reading had an option to sign him on a permanent deal at the end of the loan spell. He scored his first goal for Reading in the home match against Huddersfield Town on 3 November 2015. On 22 August 2016, John returned to the Championship, to join Wolverhampton Wanderers on a season-long loan. After an injury-ridden loan spell at Wolves, limiting his game time to a total of 71 minutes in all competitions, his loan was cut short on 13 January 2017 and he instead joined Deportivo de La Coruña on loan until the end of the season. In August 2017, it was reported that Ola John refused to be loaned to Panathinaikos and to Qarabağ.
Vitória de Guimarães
On 21 July 2018, John signed a three-year contract with Vitória S.C. in Primeira Liga.
As a two-year-old, John fled with his mother and brothers from Liberia to the Netherlands. His father was killed during the First Liberian Civil War. He did not return to the African continent until the U-17 World Championship in Nigeria in 2009. As a child, he played at the amateur club VV DES in Nijverdal. Like his brothers Collins and Paddy, Ola joined the youth academy of Twente.
