Last offseason, Michael King was finishing up his rehab for a fractured right elbow and then beginning a careful buildup for the season as a reliever.

This winter, he will be preparing to take on a full-time starter’s workload with an expected spot in the Yankees’ rotation.

After King nailed his late-season audition to move back into a starting role — he posted a 1.88 ERA with 48 strikeouts across 38 ¹/₃ innings in eight starts — manager Aaron Boone confirmed that he anticipates the right-hander being part of the rotation next year.

King’s stuff held up in longer outings as well as the Yankees could have hoped.

Now the only question is whether he can physically handle the heavier workload.

“I think I have even more reinforcement in there [the elbow],” King said with a grin of his surgically repaired body part. “Knock on wood, I had zero issues the whole year. … I’m looking forward to seeing how we go 150-plus innings.”

Of course, plans can always change depending on how the Yankees attack the offseason, especially with the team expected to be in the race for Japanese star right-hander Yoshinobu Yamamoto.

Either way, King plans to arrive at spring training ready to reinforce his grip on a starting spot.

“I’ve always said, it’s almost more fun and more of a challenge if they do sign a couple guys and in spring training, [I’m] coming in and saying, ‘You’re going to realize that I’m better than what you’re putting out there,’ ” King told The Post on the final weekend of the regular season. “That sounds cocky, but that’s the approach you gotta have when you’re trying to get the spot you want.”

That mindset has paid dividends for King so far.

A former starter in the minor leagues — where he threw a career-high 161 ¹/₃ innings in 2018 — and occasionally as he was breaking into the big leagues, King found a steady role as a multi-inning weapon out of the bullpen.

When the Yankees were hit by injuries to their starters this spring, King offered his services, but the Yankees declined since they were still building him up slowly from the elbow injury.

By August, though, with more injuries to the rotation and some more depth in the bullpen, the Yankees decided to give King a runway to start.

“I’d say [it went] probably better than anyone anticipated — not to discount his ability, but you just never know when you start opening up how the stuff’s going to look,” pitching coach Matt Blake said.

Now, King knows he needs to keep proving he can do it. After finishing this season with 104 ²/₃ innings, he said he still has a chip on his shoulder because he doesn’t feel like he is treated like a starter yet and won’t be until he makes 32 starts in a season. (He also might not be paid fully like one just yet, though he should still get a solid raise in his second year of arbitration).

With the exception of last year, King has generally treated his offseasons like he will be a starting pitcher, which gives him a familiar schedule this offseason — the only difference this time around being that he is also getting married.

After making his final start on Oct. 1, he planned to take about a month off from throwing and two weeks off from lifting before getting going again.

King hinted at potentially adding another pitch to his arsenal this offseason to go with a four-seam fastball, sinker, sweeper and changeup.

He wanted to keep that in his “back pocket” for now instead of providing specifics, but he was looking forward to diving into the numbers to see how he could improve.

“When you’re away from baseball for so long — obviously it sucks that October baseball, we’re not playing in it,” King said. “I don’t want to watch everybody else and not be paying attention to my own [stuff].

“I’ll definitely take a little bit of a break — I know my fiancée would like me to take a little bit of a break — but then when I’m just sitting there and I’m bored, I’m going to be deep diving through what I could have done better.”