Kaley Cuoco agrees to marry Johnny Galecki on The Big Bang Theory

It's been seven years in the making.

And finally on Thursday night, Leonard (Johnny Galecki) proposed to Penny (Kaley Cuoco) on The Big Bang Theory after an epic on-off romance.

The nerdy scientist and the aspiring actress become engaged in the final moments of season seven's penultimate episode, begging the question: Will the finale see the two get married next week?

Finally: Leonard and Penny became engaged on Thursday night's episode of The Big Bang Theory

The episode titled The Gorilla Dissolution sees Penny become disillusioned with her career as an actress.

After getting into row with the director of a B movie, where she plays some kind of caged ape girl, the aspiring star is fired from the film.

The dramatic turn gets Penny thinking, as she begins to reflect on what's important to her.

Popping the question: The scientist proposed to the aspiring actress

Dream come true: Penny said yes

She says to Leonard: 'Getting fired from that movie was the best thing that could have happened to me.'

Adding: 'I finally realized that I don’t need to be famous or have some big career to be happy.'

'Then, what do you need?' Leonard inquires.

'You, you stupid pop tart,' the blonde says.

Leonard replies: 'Oh, then, I guess I’m in.'

And the two appear to both realise that they've just become engaged.

Figuring it out: Penny hits a low before realizing she wants Leonard

But just as fans of the show might be getting anxious over the lacklustre proposal, Leonard has one last surprise up his sleeve.

The scientist pulls out of his wallet an engagement ring that he says he's been carrying with him for the last 'couple years'.

Leonard then extends the ring before him asking: 'Penny, will you marry me?'

'Oh my God, yes!' she answers.