Rahim's team beat Alastair Cook's men by 108 runs and square the series.
Bangladeshi bowlers, led by 19-year-old Mehedi, took all ten England wickets in a single session in the second Test as Rahim's team beat Alastair Cook's men by 108 runs and square the series.
The victory saw celebrations erupt at Dhaka's Sher-e-Bangla Stadium and across the country as Bangladeshis revelled in one of the proudest moments in their sporting history.
Chasing a target of 273, England seemed to be cruising when Cook and Ben Duckett guided them to 100 without loss at tea.
But Mehedi, playing only his second Test and who celebrated his 19th birth just this week, triggered a dramatic collapse as England crumbled to 164 all out to suffer their first-ever defeat by Bangladesh in 10 Tests.
Bangladesh secured Test status in 2000 and the win was only their eighth in 95 Tests -- and the first against a full-strength side from a major country.
"It is a very big achievement in Bangladesh?s Test cricket history. It came against a very good England side but there will be a time when we will win a series 2-0 against any big team," Rahim said.
"This is a start," he told reporters after the match.
He paid tribute to the youngsters in the side, especially Mehedi who had a record match haul of 12 wickets and a series tally of 19.
"It feels great the younger players are also contributing. We have a number of performers in the team, which is always great for a captain.
"We knew the type of player he was," Rahim said about Mehedi.
"We wanted him to play against England rather than Afghanistan so that they don't know anything about him. It is all his credit that he did so well," he said.
"There's a lot to learn from him, and I know he has the calibre to do well in the future," the 29-year-old added.
Mehedi, who twice led Bangladesh's under-19 cricket team prior to the call in the senior side, took the final wicket of Steven Finn to finish with 6-77 in the innings and 12 for 159 in the match.
It was his country's best-ever bowling figure in Tests, overtaking Enamul Haque Jr?s 12-200 against Zimbabwe in 2005.
The skipper also praised opening batsman Tamim Iqbal who scored the series' highest total of 267 runs including a century in the first innings of the second Test.
"Tamim was outstanding, especially in the first innings in Chittagong. I think that 78 was greater than his double-century. He utilised his good form, which is a really good sign." Rahim said.
The wicket-keeper batsman said Bangladesh prepared spinning wickets and the pitches worked according to the hosts' plan.
"From the time we knew England were coming, we planned to make wickets that last three to four days. The sort of wicket that would help our spinners and trouble the English batsmen.
"We played well in Chittagong but I was surprised that it lasted five days. Here our bowlers executed our plans and the batsmen did well too, which made this win possible," he said.