On 17 March 2018, Salah scored four goals in a 5–0 win over Watford, which was his first hat-trick for Liverpool. In this game, he also broke a record of scoring 36 times in his debut season for Liverpool, and also became the leading goalscorer in Europe's top five leagues – overtaking Barcelona's Lionel Messi and Tottenham striker Harry Kane. Following Salah's record-breaking goal exploits former Liverpool captain Steven Gerrard stated "we are witnessing the start of greatness".
In early April 2018, he scored in both Champions League quarter-final matches against Manchester City. On 22 April 2018, Salah was awarded the PFA Players' Player of the Year award, having earlier been named in the PFA Team of the Year for the Premier League. Two days later, he scored a brace in a 5–2 Champions League semi-final first leg win over former club, Roma. In doing so, he simultaneously became the first player from Africa and the first Liverpool player to score 10 goals in a single campaign in the tournament. His double also took him to 43 goals for the season across all competitions, surpassing Roger Hunt's tally of 42, and making him Liverpool's second-highest goalscorer in a single season, behind Ian Rush. He had previously also broken the club's record for the Premier League era, surpassing Robbie Fowler's total of 36 goals set in the 1995–96 campaign, and Fernando Torres' record of 33 for the most goals by a Liverpool player in a debut season. After his two goals and assists in the first leg against Roma, Salah featured in the second leg as Liverpool beat Roma 6–7 on aggregate to qualify for the final for the first time in eleven years. He would then become the Premier League's all-time goalscorer for a 38-game season, registering his 32nd league goal in a 4–0 win against Brighton & Hove Albion en route to being awarded the Premier League Golden Boot.
In the 2018 UEFA Champions League Final against Real Madrid, Salah injured his left shoulder in the 30th minute. After initially carrying on, he left the field in tears after going to ground in a challenge with Madrid defender Sergio Ramos; the match ended in a 3–1 defeat. The Egyptian FA stated that this would have no effect on his playing at the 2018 World Cup in Russia and that Salah would still be named in the team's final squad on 4 June. The day after the match, Ramos wrote a message and sent him good wishes.
On 2 July 2018, Salah signed a new long-term contract with Liverpool. Manager Jürgen Klopp said the news was important as a statement of intent in terms of Liverpool's status in the football world in having Salah commit himself further to the club. On 12 August, Salah scored his first goal of the season and Liverpool's first overall goal of the season, in a 4–0 win over West Ham United. On 20 August, in a 2–0 away win over Crystal Palace, Salah played a part in both of Liverpool's goals; winning a penalty for the first after being kicked in the shins twice, and providing an assist for Sadio Mané for the second. On 25 August, Salah scored the only goal in Liverpool's 1–0 win over Brighton.
On 30 August 2018, Salah was named on the three-man shortlist for the UEFA Men's Player of the Year, coming in third place, and was also included on the three-man shortlist for the UEFA Forward of the Season, coming in second place. On 3 September he was named on the three-man shortlist for the Best FIFA Men's Player, finishing third. Amid controversy and online protest, Salah received the 2018 FIFA Puskás Award for goal of the year, the winning strike his goal at Anfield in his first Merseyside derby. On 24 October, Salah scored twice against Red Star Belgrade in the UEFA Champions League group stage, with his second goal his 50th for the club. With 50 goals in 65 games he is the fastest player in Liverpool history to reach the half century.
Salah features in EA Sports' FIFA video game series: on FIFA 18 he had a rating of 87 and a potential of 90 following his displays for Liverpool. In a 2018 poll by FIFPLAY, a website run and made for the game's fans, Salah ranked first (ahead of Lionel Messi) on who should be the global cover star for FIFA 19, obtaining 77 percent of the total number of votes.
In March 2018, Salah appeared in an advertisement for Vodafone Egypt. Filmed visiting several Merseyside landmarks, the video was originally released in Arabic (but was also translated to English).
During his time in Egypt, Salah's family was once robbed, however, the thief was caught and arrested by police, with Salah's father preparing to press charges against him, but Mohamed convinced him to drop the case. Afterwards, Salah helped the thief financially, giving him some money and trying to find him a job. In February 2018, following a match against Tottenham, Salah donated a replica shirt to young supporter Mohamed Abdel Karim, who was previously pictured wearing a jumper reading Salah's name and shirt number. Moreover, Mohamed Salah has helped more than 450 families by giving them monthly allowances and he also helped the government by giving approximately $300,000 when the country was in a bad situation.