It's the first final for the South Africans, who go on to meet the Hurricanes in Wellington next weekend, where the hosts thrashed the Chiefs 25-9 on Saturday night.
First-five Elton Jantjies displayed a full array of skills at Ellis Park as the Lions confirmed the regular-season standings where they finished second behind the Hurricanes.
The Springbok scored his team's opening try, kicked over key points in his 22 point-haul, and provided the highlight of the game - a cross-field kick in the second half that found his captain Jaco Kriel on the wing and allowed the loose forward to go over for a sublime try.
The Lions did ride their luck at times but outscored the Highlanders by five tries to four.
Jantjies crossed over first in the 12th minute in what was effectively a team try as the Lions sped the ball through several phases before Jantjies was able to burst through their defence and cross over with a short sprint.
An error in the Highlanders backline allowed Rohan Janse van Rensburg to pick up a stray pass and run more than half the field to extend the Lions' lead in the 24th minute.
That misfortune for the visitors was compounded soon after when flanker Elliot Dixon dropped the ball as he was attempting to dot down, having already crossed the Lions' tryline after some brilliant handling and pop passes from the Highlanders' backs.
A 17-6 lead at half-time was extended straight after the break by Jantjies converting a tough penalty and then breaking the line to put Courtnall Skosana free for the third try for the Lions and a 25-6 lead in the 46th minute.
Centre Matt Fades scored as the Highlanders made a quick response but another penalty from Jantjies was followed by his brilliant vision in the 55th minute to set up Kriel and effectively secure the result.
Liam Sopoaga scored for the visitors in the 66th minute, but any thoughts of a dramatic comeback ended when Lourens Erasmus scored for the South African side with seven minutes to go.
There were two late consolation tries for Highlanders but Waisake Naholo and Joe Wheeler's late efforts served only to reduce the winning margin.
Highlanders co-captain Ben Smith congratulates Lions opposite Warren Whitely after the game Photo:Photosport