The Belgium frontman has been sidelined with an ankle problem since colliding with team-mate Gareth Barry in the 4-0 Merseyside derby defeat at the end of January.
But Martinez has confirmed that Lukaku is close to full fitness, but looks set to have to wait until next month's visit of West Ham to return to the first team as he will be ineligible to face parent club Chelsea a week on Saturday.
"We had positive news on Romelu," he said. "He's back with us and will be ready very soon - we're looking at next weekend."
|8/1||Everton are 8/1 with Betway to finish in the top four|
"The team has been working very well as a defensive unit and we are doing great on the ball," he continued. "We are becoming very strong.
"The league never ceases to surprise us. There are still many, many points to play for.
"It will be an interesting rally from now until the end of the season. There are many aspects to affect each team in the final third.
"Nothing is decided yet. Everything is there to be won.
"We all know there is a real unity in our dressing room with a great core that others follow. There are great characters in there."
Martinez also responded to recent rumours linking loanee Gareth Barry with a permanent move to Arsenal at the end of the season.
"The idea with Gareth was to make sure he could return to his best and enjoy playing for Everton," he added. "We'll sit down in the summer."